Unearthed: Mayan City of Blood (S1, E1) | Full Episode

Narrator: CHICHEN ITZA, A SPECTACULAR ANCIENT MAYA CITY SHROUDED IN MYSTERY AND MYTHS. IT'S THE GREATEST ANCIENT CITY IN THE WORLD. Narrator: IT'S A JUNGLE METROPOLIS WITH A HIDDEN UNDERWORLD AND DARK SECRETS.

WHAT HAPPENED TO THIS LOST CIVILIZATION? THE BIG QUESTION THAT DRIVES US IS WHY PEOPLE WERE HERE. Narrator: HOW AND WHY WAS THIS VAST CITY BUILT?

AND DID THE PEOPLE LIVING HERE PRACTICE HUMAN SACRIFICE? THE ONLY WAY TO SOLVE THESE MYSTERIES IS TO GO DEEP INTO THE HEART OF THE MAYAN CITY. EXPLORING ITS STRUCTURES STONE BY STONE WILL HELP US UNEARTH THE ASTONISHING SECRETS AT THE HEART OF THIS ANCIENT WONDER.

--<font color="#FFFF00"> Captions by VITAC --</font><font color="#00FFFF"> www. vitac. com</font> CAPTIONS PAID FOR BY DISCOVERY COMMUNICATIONS CHICHEN ITZA, MEXICO.

A THOUSAND YEARS AGO, THIS WAS A POWERFUL WORKING CITY. . .

HOME TO 30,000 PEOPLE -- THE ANCIENT MAYA -- A CIVILIZATION KNOWN FOR THEIR REMARKABLE SKILL IN ASTRONOMY, MATHEMATICS, AND ARCHITECTURE. AND FOR THEIR BLOOD-CURDLING RELIGIOUS RITES. ARCHEOLOGIST MEMO DE ANDA HAS SPENT MUCH OF HIS LIFETIME TRYING TO MAKE SENSE OF THIS MYSTERIOUS JUNGLE CITY AND IT'S AWE-INSPIRING BUILDINGS.

WE'RE JUST SCRATCHING THE SURFACE. THAT'S LITERALLY WHAT WE'RE DOING. I'M SURE THIS BUILDING IS STILL HIDING MANY, MANY SECRETS INSIDE.

Narrator: THE RUINS OF MORE THAN 30 ANCIENT STRUCTURES AND TEMPLES LIE HIDDEN HERE AMONGST THE TREES, INCLUDING THIS IMMENSE PYRAMID. THE CASTILLO, OR TEMPLE OF KUKULKAN, ONE OF THE NEW SEVEN WONDERS OF THE WORLD. BUILT FROM TENS OF THOUSANDS OF LIMESTONE BLOCKS, IT TOWERS 100 FEET HIGH -- AS TALL AS A 10-STORY BUILDING.

AT ITS PEAK, A SACRED TEMPLE DEDICATED TO THE SERPENT GOD KUKULKAN. ON EACH SIDE, STEEP STEPS THAT REFLECT HE MAYA CALENDAR. AND AT THE BASE, SERPENT HEADS LINKED TO THE EQUINOX.

THIS 60,000-TON STRUCTURE IS A MARVEL OF ANCIENT ENGINEERING. De Anda: THIS IS ONE OF THE MOST WONDERFUL BUILDINGS FROM THE ANCIENT WORLD. IT'S A DEMONSTRATION OF POWER, A DEMONSTRATION OF SPIRITUALITY, A DEMONSTRATION OF SCIENCE.

IT'S AN IMPORTANT BUILDING. Narrator: WHY DID THE ANCIENT MAYA BUILD THIS SPECTACULAR CITY IN THE JUNGLE? AND HOW DID THEY SOURCE THE MANY THOUSANDS OF TONS OF STONE NEEDED TO BUILD HUGE TEMPLES AND PYRAMIDS LIKE THIS?

ONE-THIRD OF A MILE FROM THE MAIN PYRAMID, MEMO IS SEARCHING FOR CLUES. IT SEEMS THIS IS NO ORDINARY JUNGLE. THE MAYA DIDN'T HAVE TO REALLY GO FAR AWAY TO FIND THE MATERIAL TO BUILD THEIR BIG CITIES.

LIMESTONE -- IT'S EVERYWHERE. THE MATERIAL IS BENEATH THEIR FEET -- ALL THIS MATERIAL IS RIGHT THERE. Narrator: THE LIMESTONE LAY WITHIN VERY EASY REACH.

THE SOIL IS VERY, VERY THIN. IT'S NOT EVEN TWO CENTIMETERS OF SOIL THAT'S LAYING OVER THE HUGE LIMESTONE BEDROCK. IT'S LIMESTONE ALL AROUND US.

IT'S ACTUALLY THE WHOLE PENINSULA. IT'S A BIG LIMESTONE PLATFORM. Narrator: LIMESTONE WAS THE CRUCIAL INGREDIENT THAT ALLOWED THE MAYA TO CONSTRUCT CHICHEN ITZA'S GREAT BUILDINGS.

WORKERS MINED IT IN THIS QUARRY JUST 500 YARDS FROM THE CASTILLO PYRAMID. MEMO UNCOVERS SOME EXTRAORDINARY EVIDENCE TO PROVE IT. RIGHT HERE, WE CAN SEE A PRE-FORM.

IT'S A HUGE PIECE OF ROCK -- OF LIMESTONE -- THAT THEY STARTED WORKING. 'CAUSE, SEE, THIS IS PERFECTLY ROUND, AND WE CAN SEE ON ONE SIDE THE START OF THE FORMATION OF A MOUTH OF A SNAKE. BUT SOMEHOW, THEY LEAVE IT HERE.

MAYBE BECAUSE IT GOT BROKEN. Narrator: A REMARKABLE CLUE CARVED BY A MAYA CRAFTSMAN A THOUSAND YEARS AGO. De Anda: AND IT SHOWS US BY BEING HERE IS THAT THEY OBTAINED THE MATERIAL, AND THEY WORK IT RIGHT HERE.

THEY TAKE IT WHEN IT WAS FINISHED UP TO THE CITY. SO THAT'S PRETTY AMAZING. Narrator: THE LOCAL GEOLOGY PROVIDED CHICHEN ITZA'S BUILDERS WITH AN ENDLESS SUPPLY OF LIMESTONE.

BUT THERE'S A FURTHER MYSTERY. THE ANCIENT MAYA HAD NO ACCESS TO METAL TOOLS. HOW DID THEY GET THIS STONE OUT OF THE GROUND?

De Anda: IT IS INTERESTING, AND IT'S AMAZING AT THE SAME TIME. HOW CAN THEY BUILD THESE FANTASTIC CITIES ONLY WITH STONE TOOLS? Narrator: THE RESOURCEFUL MAYA CAME UP WITH AN INGENIOUS SOLUTION.

THEY USED SHARDS OF RAZOR-SHARP STONES LIKE CHERT, SOMETIMES ATTACHING THEM TO WOODEN STICKS. THEY GOUGED DEEP CHANNELS INTO THE GROUND, CARVING A CHECKERBOARD PATTERN INTO THE LIMESTONE ROCKS. THE WORKERS DUG DOWN UNTIL THEY REACHED A NATURAL BREAK IN THE LIMESTONE BEDROCK.

THIS WAY, THE CHECKERBOARD BLOCKS WOULD CRACK AWAY FROM THE GROUND. THEN THEY USED WOODEN LEVERS TO PRY THE BLOCKS OUT. HOW MUCH EFFORT DID IT TAKE TO REMOVE HEAVY LIMESTONE BLOCKS WITHOUT MODERN MACHINERY?

TO FIND OUT, MEMO IS HEADING TO A STONE MASONS YARD IN MERIDA, ABOUT 70 MILES FROM CHICHEN ITZA. THE STONE MASONS ATTEMPT AN EXPERIMENT. THEY USE WOODEN LEVERS TO TRY TO EXTRACT A TWO-TON LIMESTONE BLOCK, JUST AS THE ANCIENT MAYA WOULD HAVE DONE.

De Anda: ALL THE STONES THEY PUT THERE TO MAKE A LEVER. I THINK WE PUT A LITTLE BIT TOO MANY. SO WE NEED SPACE FOR THE BIG LEVER.

THESE GUYS ARE EXTRAORDINARILY SKILLFUL AND STRONG. I MEAN, THEY'RE GREAT. SO FAR, SO GOOD.

[ LAUGHS ] Narrator: SHIFTING THE LIMESTONE THE OLD FASHIONED WAY CLEARLY REQUIRED BOTH TECHNIQUE AND PLENTY OF MANPOWER. De Anda: TODAY, THAT I HAVE THE OPPORTUNITY TO MOVE THIS RELATIVELY SMALL STONE AND IT WAS SO HARD. AND THERE WERE A LOT OF PEOPLE, I REALIZED HOW HARD IT WAS.

AND I'M GETTING MORE AND MORE AND MORE RESPECT FOR THE MAYA, FOR WHAT THEY DO. IT'S AMAZING. WOW, THAT WAS GREAT.

[ LAUGHS ] THESE GUYS ARE GREAT. [ APPLAUSE ] WOW. Narrator: MOVING ONE STONE WAS BACK-BREAKING WORK.

YET THIS PYRAMID IS MADE OF TENS OF THOUSANDS OF LIMESTONE BLOCKS. HOW DID THE ANCIENT MAYA BUILD IT? THE SECRET TO CONSTRUCTING THIS AMAZING TEMPLE LIES HIDDEN INSIDE BECAUSE THIS PYRAMID ISN'T QUITE WHAT IT SEEMS.

CONCEALED BENEATH THE SMOOTH FACADE IS A LAYER OF RUBBLE. UNDER THAT, AN OLDER PYRAMID, ROUGHLY HALF THE CASTILLO'S SIZE. ITS STAIRCASE LEADS TO A SACRED TEMPLE WITH TWO CHAMBERS.

AT THEIR HEART, A THRONE IN THE SHAPE OF A JAGUAR WITH JADE STONE EYES AND WHITE FLINT TEETH AND A MYSTERIOUS RECLINING STATUE KNOWN AS A CHAC MOOL. BUILDING ON TOP OF THIS EXISTING TEMPLE WAS AN INGENIOUS WAY TO BUILD BIG AS A NEW ERA IN THE LIFE OF THE CITY DAWNED. De Anda: THE ANCIENT MAYA, THEY DID NOT DESTROY A BUILDING TO BUILD ANOTHER ONE.

THEY JUST GO AHEAD AND BUILT ON TOP OF THE OLD BUILDING. AND BUILT SOMETHING MAJESTIC LIKE THIS. Narrator: BUT WHY DID THE ANCIENT MAYA BUILD A GREAT CITY HERE IN THE MIDDLE OF DENSE JUNGLE?

Narrator: IN THE VAST LANDSCAPE OF THE YUCATAN, WHY DID THE ANCIENT MAYA CHOOSE THIS LOCATION FOR THEIR CITY? TO FIND OUT, GEOPHYSICIST RENE CHAVEZ IS 75 MILES WEST OF CHICHEN ITZA CITY. USING A NEW TECHNIQUE TO SEE BENEATH ANCIENT MAYA PYRAMIDS, HE BELIEVES THE ANSWER MAY LIE UNDERGROUND.

THIS IS ONE OF DOZENS OF ANCIENT PYRAMIDS HIDDEN IN THE MEXICAN JUNGLE. IT MAY LOOK VERY DIFFERENT FROM THE FAMOUS CASTILLO, BUT IT'S WHAT MANY MAYA PYRAMIDS LOOK LIKE BEFORE ARCHEOLOGISTS RESTORE THEM. WE HAVE TO DEPLOY THE ELECTRODES ON TOP OF THE PYRAMID.

. . Narrator: RENE'S TEAM LAYS A WEB OF ELECTRODES, WHICH THEY WILL USE TO SEND AN ELECTRICAL CURRENT THROUGH THE GROUND.

THE TEAM WILL MEASURE HOW EASILY THE CURRENT TRAVELS. THEIR READINGS WILL REVEAL IF ANY STRUCTURES OR STRANGE NATURAL FORMATIONS LIE BENEATH THE ROCKS AND SOIL. IT TAKES TIME TO PROCESS THE DATA FROM TODAY'S SURVEY.

RENE CAN ONLY HOPE IT PROVIDES RESULTS AS SPECTACULAR AS HIS RECENT FINDINGS FROM A SIMILAR INVESTIGATION AT CHICHEN ITZA'S GREAT CASTILLO PYRAMID. IN THIS MODEL, EACH COLOR REPRESENTS A DIFFERENT GEOLOGICAL MATERIAL. RENE'S RESULTS REVEAL SOMETHING EXTRAORDINARY.

HIDDEN DIRECTLY BENEATH THE CASTILLO PYRAMID, BELOW A FIVE-YARD-THICK LAYER OF LIMESTONE SITS A GIANT UNDERGROUND CAVE FULL OF WATER -- A FORMATION KNOWN AS A CENOTE. THE CAVE CONTAINS AS MUCH WATER AS SIX OLYMPIC SWIMMING POOLS. IT EXTENDS OVER 65 FEET UNDERGROUND.

BUILDING A PYRAMID RIGHT ON TOP OF A CAVE FULL OF WATER MIGHT SEEM SURPRISING, BUT ITS EXISTENCE HERE HAS DRAMATIC IMPLICATIONS FOR OUR UNDERSTANDING OF THIS ICONIC TEMPLE. WITHOUT DIGGING, THERE'S NO WAY TO ACCESS THE CENOTE HIDDEN UNDER THE CASTILLO. SO ARCHEOLOGISTS MEMO DE ANDA IS VISITING ANOTHER NEARBY CENOTE TO INVESTIGATE WHAT MAY LIE BENEATH THE PYRAMID.

De Anda: ISN'T THIS WONDERFUL? IT'S ONE OF THE MANY CENOTES WE HAVE IN THE YUCATAN PENINSULA. IT'S A WONDER OF NATURE.

HUGE CAVERN, THIS IS ESSENTIALLY WHAT CENOTES ARE. IT'S A HUGE CAVERN THAT GOT FLOODED WITH LOTS OF RAIN FOR THOUSANDS OF YEARS. AND YOU CAN REALLY FEEL THE MAGIC OF BEING HERE.

Narrator: THERE'S ONE CRUCIAL DIFFERENCE BETWEEN THIS CENOTE AND THE ONE UNDER THE CASTILLO. AT THIS CENOTE, THE ROOF HAS FALLEN IN, MAKING IT LOOK MORE LIKE A LAKE THAN A CAVE. THE ONE BELOW EL CASTILLO PROBABLY IS GOING TO COLLAPSE ONE DAY.

WE DON'T KNOW WHEN. IT HAS BEEN THERE FOR CENTURIES. SO, HOPEFULLY, NOT FOR A LONG TIME.

Narrator: UNDERGROUND LAKES LIKE THIS ARE THE REASON THE GREAT CITY OF CHICHEN ITZA WAS BUILT IN THIS AREA. THERE ARE NO SURFACE RIVERS IN THIS PART OF MEXICO. THE ONLY SOURCE OF DRINKING WATER WAS HIDDEN UNDERGROUND IN CENOTES.

BUT THESE WEREN'T JUST A SOURCE OF WATER. De Anda: THEY WERE PLACES FOR WORSHIP, AND SOMETIMES PEOPLE DON'T UNDERSTAND, BUT WHEN YOU STAND HERE AND SEE THIS BEAUTY AND FEEL THIS MAGIC, YOU UNDERSTAND. Narrator: CENOTES HAD DEEP RELIGIOUS SIGNIFICANCE AND WERE SEEN AS A PHYSICAL LINK TO THE MAYA UNDERWORLD.

IS IT POSSIBLE THE ANCIENT MAYA KNEW ABOUT THE CENOTE HIDDEN UNDER THE CASTILLO? DID THEY BUILD ON TOP OF IT ON PURPOSE? MEMO BELIEVES THE MUST HAVE BECAUSE THE CASTILLO HAS A REMARKABLE RELATIONSHIP WITH FOUR OTHER IMPORTANT UNDERGROUND LAKES THAT ARE VISIBLE ON THE CHICHEN ITZA SITE.

De Anda: THIS IS EL CASTILLO OR KUKULKAN TEMPLE. ONE OF THE THINGS THAT'S AMAZING ABOUT THIS BUILDING IS THAT IT'S SITUATED RIGHT IN THE MIDDLE OF FOUR CENOTES. IT'S THE SACRED CENOTE TO THE NORTH, THE XTOLOC CENOTE TO THE SOUTH, SAGRADO CENOTE TO THE EAST, AND HOLTUN CENOTE TO THE WEST.

Narrator: THE ANCIENT MAYA DIVIDED THEIR UNIVERSE INTO QUADRANTS. THESE WERE ALIGNED WITH THE FOUR POINTS OF THE COMPASS. COULD CHICHEN ITZA'S LAYOUT BE A PHYSICAL REPRESENTATION OF THE MAYA UNIVERSE?

SO IF YOU DRAW TWO LINES, THE CENTER OF THOSE LINES IS EL CASTILLO. EL CASTILLO WAS BUILT THERE BECAUSE THE ORIENTATION OF THOSE FOUR CENOTES. Narrator: HOW THOSE ANCIENT MAYA KNEW ABOUT THE FIFTH CENOTE UNDER THE CASTILLO REMAINS A MYSTERY, BUT MEMO BELIEVES THEY DID, AND THAT THE GREAT PYRAMID WAS BUILT ON THIS SITE BECAUSE IT SYMBOLIZED THE CENTER OF THE MAYA UNIVERSE.

De Anda: WHEN THEY SAID THERE IS A CENOTE UNDER THE CASTILLO, AND YOU SEE IT'S THE CENTER OF THESE SACRED ALIGNMENT, IT MAKES A LOT OF SENSE. Narrator: THE LAYOUT OF THESE CENOTES CREATED A LOCATION WITH DEEP RELIGIOUS MEANING. BUT THE SACRED SIGNIFICANCE DOESN'T END HERE.

DURING EXCAVATIONS AT THE CASTILLO PYRAMID, ARCHEOLOGISTS MAKE AN ASTONISHING DISCOVERY. Narrator: AT THE BASE OF THE CASTILLO PYRAMID, ARCHEOLOGISTS MAKE A SURPRISING DISCOVERY. DIGGING MORE THAN SIX FEED UNDERGROUND, THEY UNEARTHED A DARK SECRET.

AMONGST THE RUBBLE, THEY FOUND SHARDS OF BONE, SKULL FRAGMENTS, AND EVEN TEETH THAT PROVE THESE REMAINS ARE HUMAN. ARCHEOLOGISTS UNEARTHED OVER 900 PIECES BELONGING TO OVER 100 DIFFERENT INDIVIDUALS. WHO WERE THESE PEOPLE?

AND WHY WERE THEY BURIED HERE? THESE MYSTERIOUS FINDS TELL AN EXTRAORDINARY STORY. AT HER LAB IN MERIDA, BIO-ARCHEOLOGIST VERA TIESLER FORENSICALLY ANALYZES THE BONES.

SHE'S UNCOVERING THE REMARKABLE SECRETS OF WHO THESE PEOPLE WERE AND WHY THEY WEREN'T GIVEN A PROPER BURIAL OR CREMATED. THESE REMAINS WERE FOUND AT ONE SIDE OF THE CASTILLO'S, AND THERE WAS A HIGH INCIDENCE OF DIFFERENT FORMS OF A NUTRITIONAL DEPRIVATION, EVERYTHING THAT HAS TO DO WITH SUFFERING, HUNGER, NOT BEING NOURISHED ADEQUATELY, OR SUFFERING FROM MANY, MANY EPISODES OF INFECTIOUS DISEASE, FOR EXAMPLE. Narrator: THESE BONES COME FROM PEOPLE ON THE FRINGES OF SOCIETY, INDIVIDUALS IN POOR HEALTH WHO WERE NOT VALUED OR WHO WERE EXPENDABLE.

IN THIS SKULL CAP, WHAT WE SEE ARE THESE DISTINCTIVE PORES. THEY MOSTLY STEM FROM EPISODES OF ANEMIA DURING INFANCY. IF WE TAKE A CLOSER LOOK AT THESE TEETH, WE CAN SEE THESE DISTINCTIVE GROOVES THAT CROSS OVER THE SURFACE.

AND THESE BASICALLY TELL US THAT A PERSON SUFFERED FROM SEVERAL EPISODES OF PHYSIOLOGICAL STRESS. Narrator: VERA FINDS EVIDENCE THAT THE SURROUNDING FLESH WAS DELIBERATELY REMOVED FROM SOME OF THESE BONES. THE BONY REMNANTS THAT WE RECOVERED AROUND EL CASTILLO SHOW DISTINCTIVE CUT MARKS.

Narrator: IT'S NO NORMAL BURIAL. WHAT THESE REMAINS SHOW IS BASICALLY PRACTICES THAT RELATE TO FLAYING TO DE-FLESHING -- BODY PROCESSING, SO TO SPEAK. Narrator: VERY BELIEVES THESE BONES ARE EVIDENCE OF GRUESOME SACRIFICIAL RITUALS.

Tiesler: THEY'RE REMNANTS THAT PROBABLY STEM FROM RITUAL ACTIONS INVOLVING ANIMAL AND HUMAN SACRIFICE. BUT THESE WERE PART OF PRACTICES CONDUCTED BY ELITE PRACTITIONERS, ELITE PRIESTS FROM CHICHEN ITZA. Narrator: THIS IS A REMARKABLE CLAIM.

HOW CAN VERA EVEN BE CERTAIN THAT REMAINS LIKE THESE BELONG TO THE ANCIENT MAYA? SOME TRULY COMPELLING EVIDENCE COMES FROM THE SACRED CENOTE -- ONE OF THE FOUR UNDERGROUND LAKES THAT SURROUND THE CASTILLO. THIS SKULL COMES FROM THE SACRED CENOTE OF CHICHEN ITZA.

IT'S CAST FROM A CHILD'S SKULL. Narrator: ONE CRUCIAL CLUE REVEALS THAT THIS CANNOT BE A MODERN SKULL -- ITS SHAPE. Tiesler: THIS HEAD FORM HAS BEEN CALLED TOP FLATTENING.

IT'S A SORT OF ARTIFICIAL SHAPE THAT HAS BEEN PRODUCED WITH BOARDS AND ADAPTED TO MAKE THE TOP OF THE HEAD MORE FLATTENED. Narrator: HEAD SHAPING WAS A COMMON MAYA PRACTICE, AND ARCHEOLOGISTS HAVE FOUND MANY MORE SKULLS LIKE THIS IN THE SACRED CENOTE. THIS HEAD IS ONE OUT OF MORE THAN A HUNDRED INFANT SKELETONS THAT WERE FOUND IN THE SACRED CENOTE.

Narrator: THE PRESENCE OF SO MANY BONES CAN BE NO ACCIDENT. THEY MUST HAVE BEEN PLACED IN THE CENOTE INTENTIONALLY -- PROBABLY AS OFFERINGS TO THE MAYA GODS. ARCHEOLOGIST MEMO DE ANDA IS NOW INVESTIGATING THIS ASTONISHING THEORY.

WHY WOULD A SOPHISTICATED SOCIETY LIKE THE ANCIENT MAYA HAVE PRACTICED HUMAN SACRIFICE? NEW CLUES LIE AT THE BOTTOM OF THIS DEEP ABYSS. Narrator: CHICHEN ITZA.

. . THIS MYSTERIOUS ANCIENT CITY IS SLOWLY GIVING UP ITS SECRETS.

INVESTIGATIONS ARE SHEDDING DRAMATIC NEW LIGHT ON ITS SPECTACULAR BUILDINGS AND RELIGIOUS RITUALS. THE REMAINS OF HUNDREDS OF VICTIMS OF HUMAN SACRIFICE HAVE BEEN FOUND INSIDE CHICHEN ITZA'S SACRED CENOTE. COULD THIS DARK PRACTICE HAVE HAPPENED AT OTHER CENOTES, TOO?

ARCHEOLOGIST MEMO DE ANDA IS CONDUCTING A MAJOR NEW INVESTIGATION AT UNDERGROUND LAKES ACROSS THE YUCATAN PENINSULA. HE'S INVESTIGATED HUNDREDS OF CENOTES OVER HIS 25-YEAR CAREER. MEMO WANTS TO KNOW MORE ABOUT THE PART HUMAN SACRIFICE PLAYED IN MAYA'S SACRED RITES.

HE'S CREATING THREE-DIMENSIONAL MODELING OF THE OFFERINGS HE FINDS TO HUNT FOR CLUES. TODAY, THIS WORK HAS BROUGHT HIM TO ANOTHER OF THE FOUR CENOTES THAT SURROUND THE CASTILLO PYRAMID. WE ARE AT CENOTE HOLTUN INSIDE CHICHEN ITZA.

AND THE ANCIENT MAYA CARVED THE ENTRANCE. IT'S SPECTACULAR, IT'S SO BEAUTIFUL. IT'S A HUGE DOME.

READY TO GO. Narrator: THE ONLY WAY TO EXPLORE THIS HIDDEN LAKE IS TO DIVE. BUT THE ONLY WAY TO REACH THE WATER IS A NEARLY 80-FOOT VERTICAL ABSEIL INTO THE DARK.

THIS IS NOT FOR THE FAINTHEARTED. THIS VAST CAVERN EXTENDS OVER 225 FEET DOWN. IT CONTAINS A LARGE UNDERGROUND LAKE OVER 160 FEET DEEP.

De Anda: GOING DOWN IN A CENOTE IS ONE OF THE BEST EXPERIENCES IN THE WORLD. Narrator: RAINWATER CARVED THIS IMMENSE CAVERN INTO THE LIMESTONE BEDROCK OVER THOUSANDS OF YEARS. De Anda: WE'RE ABOUT EIGHT, NINE METERS DOWN.

AND CAN SEE THE CULTURAL RICHNESS OF THIS PLACE. AND I DON'T WANT TO APPROACH TOO CLOSE BECAUSE IT CAN DESTROY EVERYTHING IN A SECOND. Narrator: MEMO IS MAKING SOME SHOCKING DISCOVERIES -- CERAMIC OFFERINGS, A KNIFE, ANIMAL BONES, AND HUMAN REMAINS.

EACH TIME HE DIVES INTO THIS CENOTE, MEMO TAKES HIGH-RESOLUTION PHOTOGRAPHS OF HIS FINDS FROM ALL ANGLES. BUT EXACTLY WHAT HAPPENED IN THIS MYSTERIOUS CAVERN? MEMO HAS FOUND A REMARKABLE CLUE.

De Anda: RIGHT IN FRONT OF ME, YOU CAN SEE A SHELF. IT'S A NATURAL SHELF, IDEAL TO MAKE A RITUAL DEPOSIT. Narrator: MORE BONES, OTHER OFFERINGS, AND EVEN TRACES OF CHARCOAL REMAIN ON THIS SHELF.

AMAZINGLY, IT APPEARS THIS PLATFORM WAS ONCE A SACRED ALTAR. De Anda: THIS IS PART OF THE SPIRITUAL WORLD. CENOTES ARE SILENT WITNESSES OF A VERY IMPORTANT PART OF THE ANCIENT MAYAN LIFE.

THIS IS A VERY IMPORTANT PART OF THEIR UNIVERSE. Narrator: MEMO HAS FOUND SOME TRULY EXTRAORDINARY EVIDENCE ABOUT THE RITES CONDUCTED IN THIS CENOTE. De Anda: IT WAS A VERY, VERY NICE DIVE.

AND I THINK WE GET WHAT WE NEEDED. Narrator: MEMO HAS BEEN PHOTOGRAPHING THIS SITE FOR FIVE YEARS. A CUSTOM-MADE COMPUTER PROGRAM HAS PROCESSED THE PHOTOS TAKEN SO FAR.

. . AND TURNED THEM INTO AMAZING THREE-DIMENSIONAL MODELS OF HIS DISCOVERIES.

WHAT I'M LOOKING AT RIGHT NOW IS A BIRD'S EYE VIEW OF THE WHOLE SHELF. THIS IS AN AMAZING, AMAZING IMAGE. I CAN TELL YOU WITHOUT ANY DOUBT IT'S UNIQUE IN THE WORLD.

THERE'S NO OTHER ARCHEOLOGICAL PROJECT THAT IS DOING THIS. Narrator: THE MODELS PROVIDE AN INCREDIBLE PERMANENT RECORD OF THE CENOTE'S MYSTERIOUS CONTENTS. IT'S THE NEXT BEST THING OF HAVING AN OBJECT IN MY HAND.

AND THE BEAUTY OF THIS IS THAT WE LEAVE THEM THERE. Narrator: THIS MODEL ALLOWS MEMO TO STUDY THE SHELF IN MORE DETAIL. IT EVEN SHOWS STINGRAY SPINES, ANOTHER ITEM ASSOCIATED WITH MAYA RELIGIOUS RITUALS.

STINGRAY SPINES WERE USED IN CEREMONIES, RITUALS -- RITUALS TO ATTRACT RAIN. THEY USED TO BE, LIKE, SELF-SACRIFICE. BLOODLETTING -- A LOT OF BLOOD COULD MEAN A LOT OF FERTILITY, ESPECIALLY IF THIS BLOOD COMES FROM THE PENIS.

Narrator: IS IT POSSIBLE RITUALS LIKE BLOODLETTING WERE CARRIED OUT HERE? AND IF SO, HOW DID THE MAYA UTILIZE THIS UNDERWATER PLACE WITHOUT MODERN DIVING EQUIPMENT? Narrator: ARCHEOLOGIST MEMO DE ANDA IS UNCOVERING HOW THE MAYA CONSTRUCTED A SACRED ALTAR ON A SHELF DEEP UNDERWATER WITHOUT THE USE OF DIVING EQUIPMENT.

PERHAPS THEY DIDN'T HAVE TO. MEMO BELIEVES THE WATER LEVEL IN THE CENOTE MUST HAVE BEEN MUCH LOWER WHEN THE OFFERINGS WERE LEFT HERE, THANKS TO A TERRIBLE NATURAL PHENOMENON THAT THREATENED THE ENTIRE FUTURE OF CHICHEN ITZA -- DROUGHT. THIS SHELF, PROBABLY, WAS ABOVE WATER SOME 1,200 YEARS AGO, WHEN THIS PLACE WAS DRY.

AND MAYBE IT WAS DRY BECAUSE OF THIS BIG DROUGHT. SO THIS SHELF, THIS LEDGE SHOULD HAVE BEEN EXPOSED. Narrator: THE SHELF LIES NEARLY 100 FEET DOWN, TUCKED AWAY AT THE FAR EDGE OF THE CAVERN.

AS DROUGHTS HIT, THE WATER LEVEL IN THE CENOTE DROPPED, EXPOSING THE SHELF. THE MAYA PROBABLY CLIMBED DOWN INTO THE CENOTE USING A LADDER BUILT FROM PIECES OF TREE TRUNK TIED TOGETHER WITH FLEXIBLE BRANCHES. THEY COULD DESCEND INTO THE CENOTE TO LEAVE THEIR OFFERINGS, PERHAPS REACHING THE SHELF BY CANOE.

MANY YEARS LATER, WITH THE DROUGHTS OVER, THE WATER LEVEL ROSE AGAIN, COVERING THE ARTIFACTS AND PRESERVING THEM TO THIS DAY. WHY DID THE ANCIENT MAYA CONDUCT THESE ELABORATE RITUALS? THE MOSTLY GOD THAT THEY WERE OFFERED TO WAS CHAAC, THE RAIN GOD.

I THINK THEY MAKE THESE OFFERINGS TO ENCOURAGE RAINS. Narrator: CENOTES LAY AT THE HEART OF CHICHEN ITZA. THEY PROVIDED LIFE-GIVING WATER.

THEY HAD IMMENSE RELIGIOUS IMPORTANCE, ESPECIALLY WHEN DROUGHT HIT. AND THEY EVEN DICTATED THE LOCATION OF THE GREAT CASTILLO PYRAMID. BUT COULD THE CASTILLO'S DISTINCTIVE SHAPE HOLD HIDDEN MEANING, TOO?

COULD THERE BE MORE TO ITS OUTER APPEARANCE THAN FIRST MEETS THE EYE? De Anda: IT'S MUCH MORE THAN A BUILDING. YOU SEE THE PERFECTION IN THE LINES.

BUT WHEN YOU KNOW A LITTLE BIT MORE ABOUT, IT'S -- YOU KNOW, IT'S A MATHEMATICAL BUILDING. IT'S RELATED TO ASTRONOMY. IT'S RELATED TO THE AGRICULTURAL CYCLES.

Narrator: THIS PYRAMID CONTAINS ANOTHER SECRET. IT'S ALSO A MONUMENTAL CALENDAR FOR THE CITY. 18 STONE TERRACES REPRESENT THE 18 MAYA MONTHS OF THE YEAR.

91 STEPS ON EACH SIDE, PLUS THE TOP PLATFORM, GIVE 365 STEPS -- ONE FOR EACH DAY OF THE YEAR. AND TWICE A YEAR ON THE EQUINOX, THE SUN CASTS A SHADOW SO PERFECTLY ALIGNED, AN IMMENSE SNAKE APPEARS TO SLITHER DOWN THE MAIN STEPS. THIS IS THE SERPENT GOD KUKULKAN, TO WHOM THE TEMPLE IS DEDICATED.

IT'S HARD TO UNDERSTAND HOW THEY COULD MASTER THE TECHNIQUE NOT ONLY TO BUILD THIS FANTASTIC BUILDING, BUT TO MAKE IT SO BEAUTIFUL, SO INTERESTING, AND RELATE IT TO THE SUN, TO RELATE IT TO THE CHANGES OF SEASONS. IT'S GREAT. Narrator: THE ANCIENT MAYA WERE SO DEDICATED TO TRACKING THE MOVEMENTS OF THE PLANETS AND STARS THAT THEY EVEN CONSTRUCTED THIS BUILDING -- AN EXTRAORDINARY OBSERVATORY.

De Anda: WELL, THIS IS EL CARACOL. IT'S A WONDERFUL BUILDING. IT RECEIVED THAT NAME BECAUSE OF THE SPIRAL FORM.

Narrator: "CARACOL" MEANS SNAIL OR SEA SHELL IN SPANISH BECAUSE HIDDEN INSIDE THE OBSERVATORY IS A SPIRAL STAIRCASE. De Anda: THIS ONE IN PARTICULAR SERVED THE PURPOSE OF GAZING THE SKIES AND MAPPING THEM. AND THEY WERE VERY GOOD ASTRONOMERS.

THEY HAVE A VERY GOOD KNOWLEDGE OF THE MOVEMENT OF THE CELESTIAL BODIES. Narrator: THE ANCIENT MAYA DIDN'T HAVE TELESCOPES, BUT THAT DIDN'T STOP THEM FROM MAKING INCREDIBLY DETAILED OBSERVATIONS WITH THE NAKED EYE. De Anda: THIS BUILDING, IT'S ON TOP OF SEVERAL PLATFORMS, AND STANDS OUT MAYBE TO AVOID THE CANOPY OF TREES.

JUST HIGH ENOUGH FOR THE ANCIENT MAYAN ASTRONOMERS TO LOOK ALL AROUND, EVEN WHEN THE SUN IS RISING OR IT'S SETTING. Narrator: DUE TO THE CARACOL'S RUINED CONDITION, FEW OF THE OBSERVATORY WINDOWS REMAIN. De Anda: THERE IS ACTUALLY THREE OF THEM.

THEY'RE VERY INTERESTINGLY ALIGNED. Narrator: THE MAYA ALIGNED THE CARACOL WITH THE HEAVENS. THE MAIN STAIRCASE FACES THE SETTING POINT OF VENUS, ONE OF THE MOST IMPORTANT OBJECTS IN THE MAYA SKY.

THE TOWER ON THE TOP HAS WINDOWS THAT LINE UP WITH VENUS' NORTHERN AND SOUTHERNMOST POSITIONS. AND A THIRD WINDOW IS ALIGNED WITH ASTRONOMICAL SOUTH. THE CORNERS OF THE BASE PLATFORM ALIGN WITH THE SUN'S SHADOW ON THE SOLSTICE SUNRISE AND SUNSET.

INCREDIBLY, AT LEAST 20 ASTRONOMICAL EVENTS ARE INCORPORATED INTO THIS STRUCTURE. THE MAYA USED THEIR OBSERVATIONS TO PREDICT HARVESTS, DEATHS, AND EVEN GOOD TIMES TO GO TO WAR. CHICHEN ITZA.

. . A CITY SHAPED BY THE EARTH, BY WATER, AND BY THE MOVEMENTS OF THE PLANETS.

WHERE THE BUILDINGS ARE MOLDED BY BELIEFS, WHERE SACRED MEANING IS NEVER FAR AWAY. BUT HOW DID THIS CITY BECOME SO SUCCESSFUL AND SO POWERFUL? AN INVESTIGATION 125 MILES AWAY REVEALS STARTLING CLUES.

Narrator: CHICHEN ITZA, MEXICO. THIS ABANDONED CITY WAS ONCE ONE OF THE MOST POWERFUL POLITICAL AND RELIGIOUS CENTERS IN THE AMERICAS, DRAWING PILGRIMS FROM FAR AND WIDE TO ITS SACRED SITES. HOW DID PEOPLE TRAVEL ACROSS THE CITY, THROUGH DENSE JUNGLE AND SOMETIMES WATERLOGGED GROUND?

THE SOLUTION -- SACBES, A UNIQUE KIND OF ROAD. THIS AMAZING ROAD WE'RE WALKING ON NOW, IT'S ONE OF THE SACBES OR WIDE ROADS. YOU CAN SEE IT'S PRETTY WIDE.

AND IT'S HIGH. Narrator: THIS MIGHT NOT LOOK LIKE ANYTHING SPECIAL, BUT A MIRACLE OF ENGINEERING LIES HIDDEN BENEATH THE SURFACE. RAISED HIGH ABOVE THE JUNGLE FLOOR TO ESCAPE THE SWAMPY GROUND OF THE RAINY SEASON, THESE SOPHISTICATED CAUSEWAYS ARE A MARVEL OF ANCIENT ENGINEERING.

AT THE BASE, LARGE STONES ARE FIXED IN PLACE WITH ANCIENT MORTAR TO CREATE A SOLID FOUNDATION. TINY STONES LEVEL THE SURFACE, AND MASONRY WALLS ENCLOSE THE SIDES. ANCIENT PLASTER MADE FROM POWDERED LIMESTONE FORMS THE TOP LAYER, CREATING A FORTIFIED, SMOOTH PATH TO ALLOW CHICHEN ITZA'S CITIZENS TO TRAVEL ACROSS THE CITY WITH EASE.

I THINK THEY HAD A LOT OF FUNCTIONS. COMMUNICATING -- THAT'S FOR SURE ONE OF THEM. THAT'S THE MAIN USE OF ROADS.

THIS IS LIKE AN UMBILICAL CORD, JUST PULLING THE SITE TOGETHER. BUT THERE WERE A LOT OF REASONS, JUST PRACTICALLY OR SYMBOLICALLY, OR TO EXTEND THE POLITICAL BOUNDARIES. Narrator: ARCHEOLOGISTS ARE CONSTANTLY FINDING NEW CAUSEWAYS.

THE SCALE OF THOSE DISCOVERED SO FAR AT CHICHEN ITZA IS VAST. SACBES CAUSEWAYS CRISSCROSSED OVER THE CITY, CONNECTING THE MAIN TEMPLES WITH QUARRIES AND OUTLYING COMMUNITIES. ONE LED TO THE SACRED CENOTE OVER 300 YARDS AWAY, THROUGH THE JUNGLE.

OTHERS EVEN STRETCHED OUT OF CHICHEN ITZA TO DISTANT SETTLEMENTS OVER FOUR MILES AWAY. MORE THAN 90 OF THESE WHITE ROADS HAVE BEEN DISCOVERED, REVEALING THE COMPLEX NETWORK OF THIS GREAT METROPOLIS. THEY ALL LED BACK TO THE CENTER OF CHICHEN ITZA.

IN ITS PRIME, A BUSTLING CITY WITH A POPULATION OF MORE THAN 30,000. THESE SACBES WERE REALLY IMPORTANT. THEY REALLY HELPED THE CITIES TO THRIVE.

Narrator: BUT CAUSEWAYS ON THEIR OWN WERE NOT ENOUGH TO ENSURE CHICHEN ITZA'S SUCCESS. THERE WERE NO NEARBY RIVERS. IT WOULD BE HUNDREDS OF YEARS BEFORE THE FIRST HORSES ARRIVED IN MEXICO.

AND THE MAYA HAD NOT INVENTED THE WHEEL. HOW COULD PEOPLE TRAVEL LONGER DISTANCES OR MOVE GOODS FAST? 125 MILES NORTHWEST OF CHICHEN ITZA, ARCHEOLOGIST JEFFREY GLOVER AND HIS TEAM ARE SEARCHING FOR CLUES.

WATER BECAME THE HIGHWAY, YOU KNOW. YOU WOULD HAVE HUNDREDS, THOUSANDS OF THESE CANOES ANNUALLY TRAVELING UP AND DOWN THE COAST. HOME, SWEET HOME.

Narrator: THIS IS VISTA ALEGRE, THE SITE OF A MYSTERIOUS LONG-ABANDONED, COASTAL SETTLEMENT. JEFFERY BELIEVES VISTA ALEGRE WAS ONCE A SEA PORT WITH CONNECTIONS TO CHICHEN ITZA. HE'S TRYING TO FIND EVIDENCE TO LINK THE TWO SITES.

SO FAR, JEFFREY AND HIS TEAM HAVE FOUND THE REMAINS OF ANCIENT STRUCTURES, SHARDS OF OBSIDIAN -- A ROCK USED IN TOOLS -- AND FRAGMENTS OF POTTERY. BUT A KEY CLUE COMES FROM A PARTICULAR VARIETY OF POTTERY KNOWN AS BALANTUN BLACK ON SLATE. Glover: SO THIS IS BALANTUN BLACK ON SLATE.

IT HAS THAT LOVELY TRICKLE DESIGN THAT WAS REALLY POPULAR ACROSS THE YUCATAN FROM THE CLASSIC PERIOD. YOU KNOW, THE COOL THING ABOUT THIS, RIGHT, IS THAT IT'S A DOMESTIC WARE THAT'S VERY COMMON AT CHICHEN. IT'S WHAT YOU TYPICALLY WOULD FIND IN HOUSEHOLDS AT CHICHEN.

YEAH, I MEAN, IT DOESN'T SEEM LIKE MUCH. IT'S JUST A BIT OF BROKEN POTTERY. BUT IT CLEARLY DEMONSTRATES A LINK BETWEEN OUR REGION AND THE CHICHEN REGION.

Narrator: FROM THE POTTERY EVIDENCE, WE KNOW THAT THIS SETTLEMENT WAS LINKED TO CHICHEN ITZA. BUT WHAT EXACTLY WAS THIS PLACE? A PORT TO PROVIDE TRADERS EN ROUTE TO CHICHEN WITH FOOD AND PROVISIONS?

OR SOMETHING MORE? AN OFFICIAL OUTPOST THAT CHICHEN ITZA CREATED TO CONTROL SEA TRADE? JEFFREY HOPES HIS WORK HERE WILL ONE DAY SOLVE THIS RIDDLE.

EITHER WAY, IT APPEARS VISTA ALEGRE WAS ONE COG IN A HIGHLY EFFICIENT TRADING MACHINE THAT SERVED THE GREAT CITY OF CHICHEN ITZA. LONG-DISTANCE TRADE WAS CONDUCTED BY SEA AND BASED AROUND THE MAYA CANOE. EACH CANOE WAS UP TO 60 FEET LONG AND COULD CARRY SEVERAL TONS OF CARGO.

EACH PORT WAS ABOUT 25 MILES FROM THE NEXT -- THE DISTANCE THAT COULD BE TRAVELED BY CANOE IN ONE DAY. THIS POWERFUL TRADE NETWORK STRETCHED ALL AROUND THE COAST. THE STEPPING STONES LED TO CHICHEN ITZA'S MAIN PORT -- ISLA CERRITOS.

UP TO 400 CANOES TRADED HERE AT ONE TIME. THIS LUCRATIVE PORT STRENGTHENED CHICHEN ITZA'S POWER OVER THE WHOLE PENINSULA. Glover: THAT'S WHAT WOULD HAVE REALLY FUELED THE CITY, THAT IT GREW INTO A HUGE CITY, I THINK, THROUGH THE RELIGIOUS SIGNIFICANCE AS A PILGRIMAGE CENTER WAS IMPORTANT.

BUT IT BEING AN ECONOMIC JUGGERNAUT WAS, I THINK, PROBABLY MORE IMPORTANT TO ITS SUCCESS. Narrator: TRADE HELPED CHICHEN ITZA TO THRIVE. THE CITY GREW RICH SELLING SALT, CACAO, AND TEXTILES, AND BROUGHT IN PRECIOUS STONES SUCH AS OBSIDIAN USED TO CREATE TOOLS.

BUT, SOON, THE MIGHT WOULD FALL. BY THE END OF THE 11th CENTURY, CHICHEN ITZA WAS IN MAJOR DECLINE. WHAT COULD HAVE CAUSED THIS POWERFUL CITY-STATE TO COLLAPSE?

MEMO BELIEVES THE ANSWER LIES IN THE CENOTES THAT WERE SO IMPORTANT TO THE ANCIENT PEOPLE OF THIS REGION AND IN THE EVIDENCE THEY CONTAIN OF DROUGHT. De Anda: WE HAD FOUND THAT THE SITE HAD TO OVERCOME A HUGE DROUGHT, 5, 10, OR MAYBE 15 YEARS WITHOUT RAIN. THEY HAD NO AGRICULTURE.

SO NO WAY TO FEED THE PEOPLE. WE HAVE FOUND THIS EVIDENCE IN CENOTES WHERE WE COULD SEE HOW THE WATER LEVEL LOWERED. Narrator: UNDERGROUND LAKES WITH THEIR SEEMINGLY BOTTOMLESS SUPPLY OF FRESH WATER HAD BEEN THE KEY TO CHICHEN ITZA'S SUCCESS.

NOW AS THAT WATER RAN LOW AND THE HARVESTS FAILED, CHICHEN ITZA'S GLORY DAYS HAD COME TO AN END. THE RULERS, THE KINGS OF THE MAYAN AREA, THEY CALLED THEMSELVES DESCENDENTS OF THE GODS. SO THEY ATTRIBUTED THEMSELVES A DIVINE ORIGIN.

SO WHEN THEY CANNOT, COULD NOT PRODUCE WATER, PEOPLE MUST HAVE BEEN VERY, VERY ANGRY. SOME PEOPLE MOVING AWAY, SOME OTHERS TRYING TO GET THE POWER AND TO CONTROL. Narrator: CHICHEN ITZA WAS GRADUALLY ABANDONED AND RECLAIMED BY THE JUNGLE.

ITS SECRETS WERE ALMOST LOST FOREVER. BUT THANKS TO INVESTIGATIONS BY ARCHEOLOGISTS AND SCIENTISTS, THE MYSTERIOUS CITY OF CHICHEN ITZA IS BEGINNING, LITTLE BY LITTLE, TO GIVE UP ITS BEST-KEPT SECRETS. THE INGENIOUS STRUCTURE OF ITS SACBES CAUSEWAYS, THE ANCIENT PYRAMID HIDDEN INSIDE THE CASTILLO, AND THE HUMAN REMAINS IN ITS VERY FOUNDATIONS.

THESE MAKE CHICHEN ITZA ONE OF THE MOST AWE-INSPIRING ANCIENT WONDERS EVER BUILT.