How Vitruvius and the Romans Changed Architecture: A Survey of Classical Architecture, Part II

This next session follows our discussion of the architecture of ancient Greece. We will now look at Roman architecture with emphasis on the treatise for the late Republican period architect Vitruvius. In general, Roman Republican period architecture retained an essentially Greek understanding of buildings as sculptural objects arranged for maximum visual effect in loosely structured spaces.

The image in this slide is a reconstructed view of the Roman Forum, but it could understandably be mistaken, at first glance, for a Greek sanctuary. The rise of Rome begins with the growing influence and eventual hegemony of a small agrarian town over its neighbors in the Italian peninsula. These neighbors included the Etruscans, who had adopted many customs and taste in art and architecture from the Greeks, who had established colonies in southern Italy and Sicily.

Like the Etruscans, the Romans absorbed Greek culture, to the point of transforming their pantheon of gods to correspond closely with that of the Greeks. In the 3rd century BC Alexander the Great’s far flung empire in the east fractured into numerous smaller Greek kingdoms, which were continually at war with each other. Seizing their opportunity, the Romans asserted themselves militarily across the Greek world, including north Africa, and continued their march westward into Iberia and Gaul, and northward into Britain.

At the height of the Roman empire the Mediterranean had become a Roman ‘lake’ of sorts. We ended our survey of Greek architecture by noting that the Romans adopted the Greek tendency to treat buildings as discrete objects set on large terraces that negotiated irregular terrain. An example of a Roman site that emulates a Greek sanctuary on a steep slope is the terraced temple of Fortuna Praeneste, at Tivoli, near Rome.

You will note, however that in this case, there is an overriding axial, frontal symmetry to the complex, and a somewhat different attitude toward spatial enclosure, which is here more uniform. For all its similarities, Roman architecture diverges from that of Greece in a number of important ways. Besides their penchant for frontal symmetry and spatial uniformity, the Romans were inclined to classify and standardize things having to do with character, form and proportion.

As this passage from Pliny the Elder’s Natural History shows, the proportions of columns are treated as definitive. Thus, Doric columns are made out to be six times as tall as their base diameter is wide; Tuscan are seven; Ionic are nine; and Corinthian are nine and ¾. Such standardization was never embraced in Greece, where buildings of the same type usually have parts with significantly different proportions.

Another difference is in the understanding of the relationship between walls and columns. The Greeks thought of buildings as columnar structures, and used walls as infill between the columns. An example of this approach is the Monument of Lysicrates in Athens, where although the columns are engaged, and their back sides were designed to remain hidden from view, they were in fact finished in the round, and the spaces between them filled with individual wall panels.

The building, in other words, was conceived as a columnar tholos, like the Tatton Monument in Yorkshire, which faithfully reproduces the ancient edifice, minus the walls. Temple F at Selinus in Sicily, at top right, also employs walls as infill partitions. By contrast, the Roman temple known as the Maison Carree in Nimes, France, shown below, treats the engaged columns as half-columns set against a single, uninterrupted wall.

These two, radically different understandings of walls and columns produce thoroughly different results in the treatment of certain aspects of buildings, especially interior spaces. An example of such a difference is in the way Greek and Roman Doric entablatures handle external corners. In these paired images, you will note that whereas the Greek example on the left turns the corner with a triglyph, which represents a structural beam, the Roman Doric example on the right - which is actually an 18th century building treated in the Roman manner - does so with a metope fragment.

This is because the Romans were more comfortable handling the problem of the corner triglyph at the level of the frieze, and treating triglyphs as attached decorative elements. You will also note the much less prominent echinus bowl in the Roman capital, shown on the right in comparison with a Greek example, and the introduction of a neck molding called an astragal. Note, too, the much narrower architrave, or principal beam.

Still another difference between Greek and Roman architecture is in the conception of column responds. In the Greek examples on the left, which include Doric and Ionic buildings, the beams carried by free-standing columns are received at the walls of the buildings by antae. Although these devices have capitals and bases, their profiles are treated differently, so that they have more in common with the walls against which they are set, than the more sculpturally independent columns.

Roman buildings, on the other hand, use pilasters for column responds. These are treated like rectangular replicas of the columns in front of them. The images on the right show 18th and 19th century buildings designed in the Roman manner.

Another important difference between Greek and Roman buildings is that, whereas Greek temples stood on a krepis or krepidoma of three steps, as shown in the left-hand images, Roman buildings were raised on a podium, and approached and entered axially by way of a frontal flight of steps. The podium, which was usually proportioned to be about 1/3rd of the height of the columns above, was introduced as a way to protect temples and other buildings from occasional flooding of the River Tiber. The example in the upper right-hand image is the Maison Carrée.

It was eventually abbreviated as a pedestal, as in the columns on the Triumphal Arch of Constantine in Rome, shown in the lower right-hand image. Yet another difference between Greek and Roman buildings is seen in the treatment of the Ionic capital. In the Greek examples on the left, the channel connecting the two volutes is curved or pulvinated, whereas in the Roman examples on the right, it is straight and horizontal, and called a canalis.

One last difference which we will note, that distinguishes Greek and Roman-mannered buildings from each other, is the nature of railings. Greek buildings employed a latticework called clathri to support handrails, as can be seen in the upper story of the Stoa of Attalos in Athens, shown on the left. Although in truth Roman buildings used similar devices, which were called transennae -an image of which is shown at the top left- later Renaissance architects who revived Roman forms mistakenly assumed that small column-like candelabra that were frequently found in the ruins of ancient buildings were used to support handrails.

Despite the erroneous association, these devices, which came to be called balusters in English, were worked into the Renaissance vocabulary of forms. The right-hand images show typical Renaissance ‘potbellied’ and ‘double potbellied’ balusters. On the left are 19th and 20th century examples of Greek-style clathri.

It is considered wrong to use balusters on buildings employing a Greek formal vocabulary. Clathri may however be used on Roman-style buildings. Having outlined the principal differences between Greek and Roman architecture, we will now take a close look at the contents of the Roman architect Vitruvius’ Ten Books on Architecture, the De Re Architectura.

This document is unique for being the only one dealing with architecture to have survived from antiquity, and the first one to treat of architecture as a complete body of knowledge. For although Vitrvius consulted numerous older Greek treatises, by architects like Hermogenes, Pytheos, Rhoikos and Theodoros, and others whom he named, which are now lost, these dealt with individual buildings that were designed and built by the authors. For this reason, the De Re Architectura is an invaluable resource that casts a huge amount of light on both Roman and Greek architecture.

Marcus Vitruvius Pollio, or Vitruvius as he is more commonly known, was a 1st century BC Roman military engineer whose career took him on campaigns to, among other places, the Ionian region of Greece. His treatise, which is dedicated to the Emperor Augustus, deals with the design and construction of buildings, but also such things as military machines, sundials, clocks, etc. , which a Roman engineer at the time was also expected to produce.

His Ten Books were re-discovered in the year 1416 AD by the Italian scholar Poggio Bracciolini, in the library of the monastery of St. Gall in Switzerland, and it exerted an enormous influence on Italian Renaissance architecture. Because the material in the Ten Books is extensive and organized in a manner peculiar to the mind of a Roman military engineer, the best way to begin becoming acquainted with it is to first consider the table of contents.

It will be useful to note that of Vitruvius’s Ten Books, only the first four directly concern architectural form and composition. Books 5 and 6 describe exemplary buildings that Vitruvius was familiar with, Book 7 deals with finishes, and the remaining three Books concern such things as locating well-watered sites on which to found new towns, and the building of sundials, clocks, and military machines. We shall therefore concentrate on Books 1 through 4.

In general, Book I can be described as dealing with Theory and Design; Book 2 deals with Assemblage, and includes an account of the Origin of the Arts and Building, and descriptions of building materials; and Books 3 and 4 deal with Formal elements, which are categorized in typical Roman fashion in terms of columnar types. These are discussed mostly in connection with the design of Temples. In Book I, Vitruvius gives the Principles of Architecture, the famous ‘Vitruvian Triad’, in which he says that architecture consists of Firmness, Commodity and Delight [Firmitas, Utilitas, Venusitas].

Also listed in Book I are the ‘Terms of Architecture’, which are best thought of as design principles, similar to those applied today by architects during the design process. These are Ordering, Disposition, Shapeliness, Symmetry, Correctness, and Allocation. Book III opens with a discussion of the Principles of Symmetry, which include ideal proportions and ratios, and anthropomorphic analogies, for instance the fact that the human figure can be inscribed in a square and a circle, and gender associations of the columnar types, according to which the stocky Tuscan and Doric types are thought of as masculine, and the more slender Ionic and Corinthian types are imagined to be feminine.

Vitruvius then proceeds to describe the layout of temples, giving typical plan types, and distinguishing what he calls species, by which he means intercolumniations. Books III and IV continue with detailed descriptions of the Ionic, Corinthian, Doric and Tuscan types. The contents of the first four books are detailed in the right-hand column.

You will notice some subjects are indicated in blue font. These passages are the so-called ‘excursi’, in which Vitruvius offers short stories or anecdotes that underscore points he is making. We will review some of these as we delve into the treatise.

In his first book, Vitruvius talks about the Education of the Architect. He urges professionals to acquire both manual skill and culture. An architect, he says, “must have both a natural gift and a readiness to learn… He should be a person of letters, a skillful draughtsman, a mathematician, familiar with scientific inquiries, a diligent student of philosophy, acquainted with music; not ignorant of medicine, learned in the responses of jurisconsuls, familiar with astronomy and astronomical calculations.

” He goes on to include mathematics, optics, geometry, and history. In order to illustrate the importance of a broad education, Vitruvius offers the first of his anecdotal ‘excursi’, which is the story of the Caryatids, or Women of Caryae. He recounts a passage in the history of the Persian Wars, when the Greeks had defeated the invading forces of king Xerxes of Persia.

A Greek state called Caria had sided with the Persian enemy, and for this reason its men were put to the sword, and the women were enslaved. In order to further humiliate Caria, the Greeks required that married women continue to dress as if they were wedded. In designing the Erechtheum in Athens, the architect Mnesicles depicts these matrons condemned to forever carry the heavy lintel of the eponymous porch on the south side of the building.

Although it is now thought that Vitruvius was recounting a fanciful legend about the Caryatid porch, that had arisen in the four centuries that had elapsed since the Persian Wars, he offers the story as a way of saying that Mnesicles could not have created a building of such beauty had he not been well-read in history. The passage in Book I that has resonated most profoundly in Western architecture is the so-called Triad, which are the principles of Firmness, Commodity and Delight. The Triad evokes the form of a tripod, which relies on all three legs to stand upright.

Accordingly, a well-executed building must be equally sturdy, practical, and beautiful. What distinguishes the architect from the engineer, is the ability to imbue buildings with Delight, or Venusitas. Vitruvius’ Book 2 deals with the assemblage and materiality of buildings.

As in Book I, the section opens with an ‘excursus’, an account that sets up the discussion that follows. The story he tells is that of the architect Dinocrates, who wished to follow Alexander the Great on his march to India and beyond, and serve as his architect. After many unsuccessful attempts to communicate his intentions to the king, Dinocrates resolved to seek him out in person.

He devised a clever ruse to make it past the guards in Alexander’s camp. Being a man of impressive stature and build, Dinocrates dressed up like the demi-god Hercules, complete with lionskin and club, and strode resolutely into the camp. The guards did not challenge him, thinking he might in fact be Hercules.

When asked by Alexander who he was, Dinocrates introduced himself and tried to impress him by describing his plan to shape Mount Athos into the figure of a man, in whose left hand an entire city would be built. Intrigued, Alexander then asked if there were fields about which could supply produce to sustain the inhabitants. When Dinocrates admitted that there were none, Alexander praised his vision but criticized its impracticality.

In the end, the young king welcomed Dinocrates as his architect, and he went on to design the great city of Alexandria in Egypt, but he had been taught by the king that great works are always the product of collaboration. The point of the story is that architects should always be ready to recognize the limitations of their knowledge. Immediately after the story of Dinocrates, Vitruvius follows with a discussion of the Origin of the Arts and of Building, in which he tells the story of the Primitive Hut.

According to the Roman author, in primitive times, humans constructed their first shelters by assembling branches and other available natural materials, to create a rudimentary roof and enclosing walls. This logical rustic edifice, argues Vitruvius, is the ancestor of all buildings. In the 18th century frontispiece by the French architectural theorist Laugier, shown on the left, a female personification of architecture points to the Vitruvian Primitive Hut as a reminder that all buildings ultimately harken back to it.

On the right are two modern examples of pavilions that emulate the Vitruvian hut. In his discussion of the Principles of Symmetry, the Roman author explains how the proportions of the various parts of the human body relate to each other. For instance, there are so many hands, heads, feet and arms, in the height of a typical person.

Many of the measurements used by the Greeks and Romans were derived from the human body; the inch, or uncia, for instance, is a word meaning ‘thumb’ in Latin. The digit, palm, foot, and cubit, or arm, are other examples of Greek and Roman anthropomorphic units of measurement, which we still use today. The metrological relief from Salamis in Greece, shown in the upper left-hand image, shows these standard units.

Vitruvius backs up his discussion with references to a lost treatise by the Greek sculptor Polykleitos, known as the Canon, in which he explains the arithmetic relationship of human body parts, including subtle differences in male and female figures. The images used here and in some of the next slides are from Prof. Ingrid Rowland’s translation of Vitruvius, illustrated by architect Thomas Noble Howe.

Vitruvius’s discussion in Book III of the hidden ratios in the human body have been made famous by Leonardo Da Vinci’s drawing of the Vitruvian man, showing how our height is equal to the length of our arms from fingertip to fingertip, and how our navel is the center of a circle described by the ends of our extended arms and legs. In Rowland and Howe’s modern illustration on the right, a more accurate image is shown of smaller, localized circles centered on the shoulders and hips, but the larger outline generally organizes around the navel. Also in Book 3, are descriptions and terms of temple Types, or plans.

As every well-informed builder today still knows, these types are: -In antis, meaning temples with a single frontal porch and columns between antae, or wall ends. -Prostyle, meaning temples with a forward porch of free-standing columns [remembering that in Greek, stylos means column and pro means forward]. -Amphiprostyle, meaning temples with prostyle porches on both ends.

-Peripteral, meaning temples with surrounding colonnaded ptera or wings. -Dipteral, meaning temples with two layers of surrounding colonnades. -Pseudodipteral, which are dipteral temples with an omitted inner colonnade that widens the ambulatory.

and -Hypaethral, which are temples without roofs, usually colossal buildings that were too large to span with ordinary beams. In listing the Species of temples, Vitruvius describes colonnades employing different intercolumniations. These were given as distances between the edges of columns.

In Thomas Gordon Smith’s illustration on the left, the following Vitruvian intercolumniations are shown: -Pycnostyle, meaning columns set one and half base diameters apart -Systyle, which are set two base diameters apart-Diastyle, set three diameters apart -Araeostyle, set more than three diameters apart … and -Eustyle, set two and a quarter diameters apart. According to Vitruvius, this last intercolumniation was considered most satisfying, hence its Greek name, eustylos, meaning ‘beautifully spaced column’. In Chapter 3 of Book III, still speaking of columns in elevation, Vitruvius describes the neck contraction or diminution, wherein column shafts become more slender at the top, and entasis, which is the characteristic swelling of the diminishing shaft as the column rises.

To explain how this parabolic curve was delineated, Vitruvius refers to a drawing, which however did not survive in his treatise. Nevertheless, we know from archaeological sites that preserve traces of the method of construction, that the curve was achieved by first drawing a circle using a compressed vertical scale, as shown in the lower left-hand image, where the center of the circle is the intersection of the line bisecting the one formed by connecting the base and neck, and the extension of the base line. By measuring outward from the center line and translating the compressed vertical scale to actual size, workmen were able to define a proper parabolic curve – the shaft’s entasis, which in Greek means ‘tension profile.

’ In Chapter 5, Vitruvius sets out the details of the Ionic type, including the capital, down to the smallest component, on the basis of equal subdivisions of larger parts. For instance, the eye of the volute is 1/18th the base diameter, and set 1/3rd of a base diameter down from the bottom of the architrave, in alignment with the edge of the lower diameter. As in his description of entasis, Vitruvius references a drawing to show how to delineate the Ionic volute, but the drawing did not survive.

This led to the development of various Renaissance solutions, some more successful than others. In the 20th century, the Roman method of setting out the volute was determined on the basis of certain antique fragments that preserved the original compass points in the eye of the volute. One fragment from the Emperor Hadrian’s Villa near Rome shows four center-points for arcs swung consecutively around the eye.

Elsewhere in Chapter 5, Vitruvius lays out the Ionic entablature, using proportions derived from the column base diameter. Thus, for instance, the height of the architrave is a half column base diameter. An example of an Ionic entablature built in the 18th century is shown below right, complete with faceted architrave, simple frieze, dentils and cornice.

Continuing on, Vitruvius describes an Asiatic Ionic base, which is to say a base of the sort used by the Ionians of Asia Minor, shown at the top of the slide; and an Attic base, favored by the Athenians. The Asiatic type comprises, from bottom to top, a plinth, surmounted by the sequence: scotia, scotia, torus. The Attic type consists of plinth, torus, scotia, torus.

Vitruvius continues by describing how to construct a pediment in the manner of the Greeks. He sets the apex of the tympanum, which is the inner triangular surface, up by 1/9th the width of the horizontal corona at the base of the pediment. Although Romans often made their pitches steeper, Vitruvius offers only this method.

His description shows his bias for Greek details and techniques. Moving on to Book 4, past his account of the Ionic type, Vitruvius returns to his discussion of symmetries in architecture, and their derivation from the proportions of the human body. He speaks of Doric and Ionic systems as masculine and feminine, on the basis of their different proportions, and refers to Polykleitos’ ideal body ratios as set out in his Canon.

This curious interpretation of the columnar types would have baffled the ancient Greeks who developed them, and saw them simply as tectonic devices proportioned and articulated in accordance with their tribal sensitivities. Vitruvius was especially interested in justifying the ratio of column diameter to height, on the basis of the foot to height ratio of idealized male and female body types. So, for example, he says of the Doric: “Finding that the foot was the sixth part of the height in a man, they applied this proportion to the column… So the Doric column began to furnish the proportion of a man’s body, its strength and grace.

Afterwards also seeking to plan a temple of Diana in a new kind of style, they changed it to a feminine slenderness with the same measurement by feet. And first they made the diameter of the column the eighth part of it, so that it might appear taller… This type because the Ionians made it first, was named Ionic… But the third type, which is called Corinthian, imitates the slight figure of a maiden. ” Also in Book 4 is Vitruvius’s story of the invention of the Corinthian capital by the Athenian Architect Callimachus, who observed an acanthus plant growing around a basket set on young child’s grave.

We have already summarized this account in our discussion of the Greek Corinthian type. Here again, Vitruvius appears to be sharing a later mythographic embellishment -what today we would call an ‘urban legend’. As we noted earlier, the Greek Corinthian capital varied from building to building, but the version that was developed by Polykleitos at Epidauros, shown on the left, appears to have served as the model for the Roman Corinthian type.

The capital on the right is from the interior of the Roman Pantheon. Like other Roman Corinthian capitals, it is more foliate than the Greek types, and the underlying bell is therefore less visible. The fleuron, or flower-like motif at the top of the capital, is now made to overlap the abacus.

Although in Republican Rome all three Greek types were used, in the imperial period, after Vitruvius dedicated his book to the Emperor Augustus, Corinthian was prescribed for all public buildings. The various parts of the Roman Corinthian capital are as follows: Rising from the moldings of the necking, in other words the astragal and fillet, there are two overlapping tiers of acanthus leaves. From behind the second tier, two cauliculus stems emerge, from the buds or junctures of which rise more fronds.

These curl up under the corners of the abacus, and beneath the fleuron. For a base, Corinthian columns use a variant of the Greek Ionic, which from bottom up consists of plinth, torus, scotia, scotia, torus. However, the Attic base, shown below right, is also frequently employed.

In Chapter 2 of his Fourth Book, Vitruvius offers a detailed description of the Doric type, including the column profiles and proportions, the entablature, and the cornice. He specifies the proportions of the various components as fractions or subdivisions of a half base diameter, which he sets as a module. In these images you can see that he indicates a metope fragment, rather than a triglyph, for the corners of the Doric entablature.

Although his description is painstaking, the Roman architect was clearly not satisfied with some of the formal problems and contradictions in the Greek Doric system. Fluting of column shafts is an important aspect of the Western columnar types. In Greece, an unfluted column was considered unfinished.

Romans sometimes omitted flutes, but used them more often than not, especially on interiors. Doric columns always have 20 flutes, whereas Ionic and Corinthian have 24. The Doric variety are shallow segments separated by sharp edges called arrises.

They are described by raising an equilateral triangle between each arris, and using the apex as the center of an arc. The flutes are made to curve more tightly as they come closer to the arris. By contrast, Ionic and Corinthian flutes are separated by narrow bands, called fillets.

A half circle is usually described between the fillets. A number of theories have been proposed to explain the origin of fluting. One these suggests that they are formalized striations left by a spade, during removal of the bark from tree trunks, to fashion column shafts.

The Vikings are known to have used bark spades to prepare logs for use in buildings. Another theory is that the Greeks were inspired by Egyptian faceted columns, like the ones shown here, at the Tombs of Beni Hasan. The Egyptian examples, however, predate the earliest Greek fluted columns by more than a thousand years, and being tombs, are unlikely to have been visited by Dorian or Ionian builders.

Still another theory is that the Greeks simply preserved their own traditions, as Mycenaean columns, which preceded the familiar Archaic and Classical period type by some 500 years, are known to have sometimes included fluting. This was usually achieved by pressing rods into plaster surfaces. This tradition appears to survive in the occasional incorporation of convex members inside the flutes of Ionic and Corinthian shafts.

A modern example of this detail, which is called reeding, is seen in the US State Department Treaty Room, shown below left, that was realized in the 1980s by architect Alan Greenberg. In Chapter 6 of his Book 4, Vitruvius provides details and proportions for doorways specific to the various columnar types. The Bank entrance shown in the slide is modeled after the Ionic doorway of the Erechtheum.

In Chapter 7 of the Fourth Book, the Roman architect offers a brief description of the Tuscan type, which was used by the Etruscan people who once lived in the Italian peninsula alongside their Latin neighbors. Although Vitruvius considered the type to be a rustic variant of the Doric, his description served to validate it and, in the Italian Renaissance, to elevate it as one of the five accepted columnar systems. The map on the left shows the historic homeland of the Etruscans in Italian peninsula, in red.

The areas in green, extending along the southern Italian and Sicilian coasts, show Greek territories. According to Vitruvius, the Etruscan temple typically had a deep hypostyle porch set in front of a cella with three separate compartments. The eaves and mutules or rafters projected out beyond the columns and walls by a quarter of the height of the columns.

On the right is a view of the east porch of the 17th century Church of St. Paul at Covent Garden in London, by the architect Inigo Jones. The building is an attempt by Jones to faithfully reproduce an Etruscan temple, as described by Vitruvius.

Always according to Vitruvius, Etruscan columns were seven times as tall as their base diameter. The capital and base were each proportioned to be ½ a base diameter in height. The capital comprised an abacus and echinus, like the Doric type, and the base consisted of a torus set on a round plinth.

Although few original Etruscan columns survive, as they tended to be wooden, Etruscan wall paintings and other artworks occasionally represent columns. From these depictions it appears that the capitals originally comprised a deep bowl-like echinus, surmounted by an abacus, very much like Archaic Greek Doric examples. The echinus transitioned to the column shaft with a small necking piece, which may have been made of bronze, to judge from the green color that it is often painted.

This device became deeper over time, so that later examples such as the one shown below left, feature a broad neck set between the echinus and an small round molding known as an astragal. An Etruscan-like capital was employed in the lower tier of the surmounted engaged columns of the Colosseum in Rome, shown here. This zone is sometimes erroneously referred to as Doric, on account of the more familiar vertical stacking of columnar types which involve a proper Doric.

Note that at the Colosseum, the lower tier also lacks a frieze of triglyphs and metopes. There is no question that that columnar type used here is Etruscan; its incorporation into an ancient monument of such importance helped, together with the Vitruvian description, to establish the Tuscan type as one of the five canonical Renaissance Orders. Although Vitruvius does not mention it, the Composite type appears for the first time in the Augustan period or 1st c.

BC, and was typically used in Triumphal Arches. It is thought to combine the three Greek types of capital, as a celebration of the Roman triumph over the Greek world, and its unification under Roman rule. Thus, the capital includes tiers of acanthus leaves, a prominent echinus, and large angled volutes.

The frieze is sometimes pulvinated, and the cornice combines Ionic dentils with Corinthian-style brackets or modillions. Despite its name and the treatment of its capital, in its other details and proportions the Composite is closely associated with the Corinthian Order. It is sometimes called the Roman, or Italic type.

It is a curious fact that Vitruvius, a Roman architect and engineer, does not describe arches in his Ten Books. Roman architecture often includes these devices, and the great arcuated aqueducts of the Roman Empire are still considered structural marvels. Vitruvius’s omission may be due to his Greek biases, for although the Greeks were familiar with the structural properties of the arch, and occasionally employed arcuation in their buildings, they relied primarily on trabeation, in other words a post-and-lintel vocabulary of forms.

The Roman arch has a specific set of associated forms and terms, which the student of architecture should be familiar with. To begin with, arches are made either of radiating bricks, shown on the left, or wedge-shaped blocks called voussoirs; In some cases they employ a ‘bent architrave’ called an archivolt, an example of which is shown below right. This Roman arch is made up of voussoirs and a central keystone.

The inside edge of the voussoirs is called intrádos, whereas the outside edge defines the extrádos. The arch springs from imposts, which are horizontal bands serving simultaneously as crowning members of the piers or abutments that support the arches. The elevational thickness of the impost blocks is usually 1/9th or 1/7th the width of the arch itself.

The center of the arch is usually placed slightly above the top of the impost, to create a stilting effect. This elevates the arch and helps to make it look fuller, as its proper height can be obscured by the projection of the impost. For this reason, the lowest voussoir, or springing block, is also sometimes called a stilting block.

Finally, the roughly triangular space between arches is called a spandrel. A motif that arose in Roman architecture and which is now an essential part of the classical repertoire, is the fornix. This is an arch flanked by columns, which is usually repeated across entire elevations, and is sometimes superimposed on different levels.

One of the earliest examples of a building with a fornix theme is the Tabularium overlooking the Roman Forum, which is shown at top left. The fornix was typically used in stoas and the elevations of theaters like that of Marcellus in Rome, on the right, and amphitheaters, like the Colosseum. Rustication also entered the classical repertoire thanks to the Romans.

Although the Greeks had used rustication for their fortification walls, under the Roman Emperor Claudius, the surface treatment was worked into formal compositions involving refined columnar expressions, fornix themes, and pedimented fronts. Examples include the Platform of the Temple of Divine Claudius, shown below left, and the Porta Maggiore in Rome, shown at bottom right. As mentioned at the start of this presentation, Roman urbanism initially followed Greek examples, that were either informal, as at the Roman Forum, or orthogonal in the Hippodamean manner, and aided by terracing when the terrain was irregular.

As in Greece, civic and religious buildings were treated as free-standing structures to be appreciated in the round. On the accession of August Caesar and the establishment of the Roman Empire, public space was increasingly enclosed and structured about a principal axis of approach. Perhaps inspired by earlier Etruscan examples, temples were directional with frontal axes, although they continued to allude to the Greek peristyle type, through the incorporation of engages columns along the flanking cella walls.

In this reconstructed model of ancient Rome, you can get a good understanding of the spatial qualities and directional nature of the Imperial forums. As the Empire expanded, permanent military garrisons were often established in conquered lands. The forts that housed the troops, known as castra, from which we derive our own word ‘castle’, were typically square in plan, and gridded.

Soldiers were trained to erect them in a single day, sometimes no less that 5 or 6 hours. They included a main avenue, the Via Principalis, which intersected with the perpendicular Via Praetoria. At their intersection there were rectangular mustering spaces, including a forum and shops to cater to the soldier’s needs.

Roman camps were essential small towns. Sometimes these impermanent castra would be replaced by durable buildings and transform into towns. New towns were called ‘coloniae’ and were laid out using the same guiding principles.

Their gridiron street pattern survives in many places, for instance Torino in north Italy, shown on the right. In these examples, the two principal intersecting streets, known as the cardo and decumanus, can still be traced. As can be seen in the plan of the Roman colony of Timgad, in Algeria, shown on the left, the cardo usually terminated in a central forum, whereas the decumanus extended the full width of the town.

The Hippodamean gridded approach is evident in the plan of the town of Pompeii, at the foothills of Mt. Vesuvius, near Naples, in Italy. Here the well-preserved urban fabric allows us to appreciate the layout of typical Roman townhouses.

These tended to present simple walled elevations on the street, with few if any windows, and to deploy along an axis extending into the middle of the block. Along this axis were an atrium with four columns supporting an impluvium, or surrounding inwardly tilted roofs, which would direct rainwater to a shallow basin. The dining room, or triclinium, occupied the center of the axis and faced the atrium.

Diners would recline in Greek fashion, but facing a central serving table or platform. Beyond the triclinum, one accessed a peristyle court, which contained a landscaped garden, often with fish ponds and fruit-bearing trees. The sequential arrangement of Roman houses is echoed in the layout of the Imperial forums, for instance the Forum of Trajan in Rome, and in Early Christian churches like the Old St.

Peter’s basilica in Rome, which was entered through a peristyle court. Other urban building types included the insula, or apartment building, such as the example from the port town of Ostia, on the left, and public Bath houses, knows as Thermae, like the enormous Baths of Caracalla, in Rome. Roman cities also included theaters, council houses known as Curiae, stadia, hippodromes, and more.

Many of these types originated in the Greek polis, or city. The rise of Christianity in the 4th century AD saw the transference by the Emperor Constantine of the Roman capital to the small Greek town of Byzantium on the Bosphorus, which is the channel connecting the Mediterranean and Black Seas. The town was renamed Constantinople, and grew into a second Rome, which stood for another thousand years.

Because it was situated in a corner of the Greek world, the Byzantine empire, as the eastern half of the Roman Empire that was ruled from Constantinople came to be called, used Greek as its official language. In 1453, Constantinople fell to the invading Ottoman Turks. During the long siege of the city, a number of learned Byzantine Greek scholars like John Argyropoulos, shown at top right, and Cardinal Bessarion, below right, took refuge in Italy.

On his arrival in Italy, Bessarion donated his vast collection to the Vatican and the Venetian Republic. This exodus of scholars and the remnants of ancient writings helped to spark the Italian Renaissance. This concludes our overview of Roman architecture.

Our next session will focus on the architecture of the Italian Renaissance and the Baroque period that followed.