"In the heart of downtown Miami between the skyscrapers and hotels lies a mystery." "Something extraordinary was recently discovered here:" "strange holes in the ground." "These holes are worth $27million." "They don't contain oil or gold, but something much more intriguing." "Nothing like this had actually ever been observed anywhere in North America." "Afraid it's a puzzle that'll take a long time to figure out." "These holes could be the most exciting find in America for decades, or they could be a costly mistake." "The discovery has sparked a furore." "In July 1998 a Florida developer started work on a luxury development on prime waterfront property where the Miami River meets Biscayne Bay," "but a routine archaeological survey of the site was to unleash an extraordinary chain of events." "When we purchased the site in March of 1998 there were five apartment buildings approximately three storeys in height that were built back in the mid part of the '40s." "We subsequently then tore down those buildings to make the site ready for the eventual construction of the 600 rental apartments." "Michael Baumann, the developer, had bought the property several years ago, had paid $8½ million for a very valuable piece of downtown real estate so thus was moving very quickly forward to get these new buildings built." "By law Baumann, the developer, had to allow an archaeological survey, so Bob Carr, the county's leading archaeologist, did a routine inspection." "Baumann wasn't anticipating any great discoveries." "America's a young country and we have a couple of hundred years of history, we certainly don't have centuries of history and therefore whatever they find, albeit very important to our civilisation and our society, it certainly cannot compare to that that you find at Stonehenge or you find at Pompeii" "or you find anywhere else throughout Europe." "At first the archaeologists removed the top layer of ground and found nothing special, but as they dug lower they were taken by surprise." "We were actually out there during the demolition and began to observe that beneath the buildings and beneath the fill there was some very significant archaeological materials." "Below the fill was a layer of ancient refuse, or midden." "It was evidence of prehistoric life." "To our surprise beneath the fill we find that at least 50% of this prehistoric site was still intact." "But this was just the start." "What they were about to find would exceed their wildest expectations." "As they carried on digging a bizarre feature came to light." "As we began to excavate within the footer trench we were able to observe in the bedrock cavities and openings." "Some of them appeared natural, but some of them, at least to me, appeared to be humanly made." "They had found strange round holes pockmarking the surface of the limestone bedrock." "The rock is porous and easily eroded, so these could be normal erosion holes or could they be man-made?" "Bob Carr and I definitely had differing opinions as to what the, the nature and origin of these holes were." "I thought they were natural solution cavities, Bob Carr thought that they were of culture origin, that they were made by human beings who once lived on this site." "They also found larger rectangular basins containing smaller holes." "The archaeologists puzzled over this." "Was it possible that the basins had a design?" "And some of them appeared to form a pattern or an arc." "Well our surveyor, Ted Riggs, being very astute about such things really was quite sure that it was an arc and in fact that the arc was part of a circle." "I noticed the formation of these four pits." "Assuming that four holes forming an arc were part of a circle" "I calculated what the radius of a circle with that arc would be." "Riggs could imagine that the curve of the four uncovered pits was just a section of a full circle so he worked out where the centre would be and the circle's dimensions." "I spray-painted a circle on top of the fill 38ft diameter." "The archaeologists brought in a digger." "We dug down through the overlying fill into the midden soil to about 10cm above the bedrock and I went behind the backfill with a metal probe trying to detect the presence of these cavities in the rock." "And as they followed the machine these other basins appeared all in sequence forming this perfect circle, exactly where we had predicted it would be." "Riggs was right." "Underneath his line was a complete circle of basins cut into the rock." "The archaeologists believed they may have found something truly remarkable:" "the remains of a mysterious ancient monument." "Perhaps it was the legacy of a long lost people." "It was very exciting because as we began to do our research and talk to our colleagues across North America we found that nothing like this had actually ever been observed anywhere in North America." "For the archaeologists it was a tantalising discovery." "Within days it became known as the Miami Circle." "Riggs believed the circle wasn't North American." "Instead he thought it was the relic of an ancient culture in Central America thousands of miles to the south." "The Olmec were the earliest of a series of great civilisations which arose from about 1,000BC." "They produced magnificent artwork carved in stone." "They were followed by other cultures such as the Maya who all built extraordinary cities with vast pyramids and temples." "No monuments of these cultures have ever been found in North America, but the idea that the Miami Circle might be Olmec or Mayan raised expectations to a fever pitch." "By February '99 public fascination with the circle was at a peak, but the site was on prime Miami real estate." "Construction of the apartments was long overdue and the developer was losing money." "It took approximately 5½ years to get to the point we were at at that juncture and invested tens of millions of dollars to get there." "The archaeologists still had so much to find out, but they were running out of time." "The builders were ready to move in." "What we told them was that they weren't going to just use our property to start an archaeological dig without paying for it." "Baumann was poised to send in the bulldozers, while protestors campaigned loudly to save the site." "The demonstrators were outside." "We learned later that several of them were armed and were planning to take over the circle." "Local officials were under intense pressure to act." "They started legal proceedings and forced the developer to sell his land to the State of Florida." "In a blaze of publicity the Miami Circle was bought, with public funds, for $27million." "A prime slice of Miami real estate was preserved for archaeological research," "but was the circle worth its price tag?" "All the big questions about the circle were still unanswered:" "what was it, who built it and when?" "The archaeologists working on the site could find no evidence that the circle was a relic of Mayan or Olmec culture." "To work out who built the Miami Circle and what it might be they looked to North American history." "Native American Indians have their own traditions of building dwellings, ceremonial centres and monuments." "The continent was once a rich patchwork of hundreds of tribes with enormously varied lifestyles." "Plains Indians, like the Sioux, were usually on the move hunting bison and living in teepees," "while people of the Ohio and Mississippi valleys were farmers and built large settlements with vast ceremonial mounds." "Desert Indians built mud structures, or pueblos, in places like New Mexico." "Although many ruins remain in North America, nowhere has the imprint of a monument or structure cut into bedrock been found until now." "So who out of all these tribes built the Miami Circle?" "Long ago the people who had lived at the mouth of the Miami River were the Tequesta Indians." "a small group of hunter-gatherers who travelled around the vast, forbidding wilderness of the Everglades and along the sub-tropical coast." "They were a remote, elusive people and neither the 16th century Spanish nor later European explorers came close enough to know much about them," "but they still wrote of the Tequesta as brutal and terrifying." "We considered our condition being among a barbarous people such as were generally accounted man-eaters." "They came in the greatest rage possible that a barbarous people could." "If you were a Spaniard arriving on a Florida beach in the 1500s your life expectancy would be about three minutes and indeed we know from accounts that many of these Spaniards were clubbed and killed immediately when they came ashore." "It had always been believed that the Tequesta were a tiny group of Stone Age fishermen living in the crocodile-infested Everglades." "They travelled by canoe foraging for food and erecting temporary shelters, but until now there was no archaeological evidence that they had ever built monuments, or even houses." "Why would a people who were not known for ceremonial structures or even settlements have built something on the scale of the Miami Circle?" "It was an extraordinary idea." "The discovery of the circle wasn't so much the conclusion of a mystery." "It was the beginning of a new one." "On site the archaeologists had to work sifting through the clue that might answer their many questions." "We have close to 1,000 bags of material that, that we excavated on the site and it's really that material that's going to tell the tale of what took place here and help us to figure out what this circular feature represents." "The first question was the circle's age, but there was no way that they could date when humans had actually cut these holes into the rock," "but the holes themselves were filled with archaeological material, such as bone and scraps of charcoal from ancient fires." "If the charcoal could be carbon dated it might say when people were living here." "We're all made up of carbon, all living things are made up of carbon." "One carbon atom in every trillion carbon atoms is radioactive." "By radioactive we mean unstable so it does what we call decay." "It decays to something else and this decay process is constant." "Every 5,500 years or so we will have one half as much carbon as we had previously and we can use this to determine the age of something." "The charcoal was dissolved and purified so that atoms of radioactive Carbon-14 could easily be detected." "The amount of decay could then be measured to give the charcoal an age." "The initial samples from the circle were two charcoal samples." "They gave us an age, oh, of about BC 50 to AD 240 or 250 something like that." "The charcoal inside the holes was 2,000 years old." "If the holes were also this old the Miami Circle would be one of the most important ancient sites in North America," "but then someone dropped a bombshell." "Just didn't sound right, Indians digging holes in limestone." "Jerald Milanich is a leading Florida archaeologist." "He was invited down to Miami to assess the find." "I got on the aeroplane and they handed me a beautiful colour aerial photo of the circle and right in the middle of it abutting one side was a rectangular thing and when I got on the plane someone hands me this and said what do you think of the septic tank?" "I said what septic tank?" "This rectangle is a septic tank that's exactly centred in, in the circle." "Zow-ee!" "It was indeed a septic tank which had served the old apartments." "To Milanich the holes in the rock could be the soakaway from the effluent for the tank." "Had Florida just paid $27million for a 1950s sewage system?" "It was an appalling idea." "Oh I think I'm very unpopular in Miami, but I think that people have to stand up for science and that you must seek out the truth." "You have to find the truth." "What would happen if it turns out that it is an 1950s septic tank drain would be disaster for archaeology." "I think archaeologists would be the laughing stock." "Was there a link between the ring of holes and the septic tank?" "Was the circle 2,000 years old, or the most expensive mistake in archaeology?" "The archaeologists had to find out." "Prior to our beginning work out here there were a series of six low rise apartment buildings on this site." "They were referred to as the Brickell Point apartments." "Those apartments were built in 1950." "The septic tank served these apartments." "In the public archives Ricisak searched through the original plumbing plans to find out if the tank had a circular soakaway." "The liquid effluent which in a typical septic tank system would then be discharged out the end of the tank to a drain field instead discharged to a sewage outfall in the sea wall and then it would just discharge untreated into Biscayne Bay." "It was clear from the blueprints that the septic tank drained through a pipe and there was no link at all between the tank and the circle of holes." "Is it merely a coincidence that this circle of holes goes right around this septic tank?" "Potentially the circle was a unique archaeological site so it was crucial to verify that the holes were truly old." "To rule out any modern connection with the circle" "Ricisak traced all the other structures that had been built on the site since the 1800s." "Although Ricisak scoured the records for anything modern to correspond with the circle, he found nothing," "but Milanich had cast serious doubt on the circle's archaeological authenticity." "The archaeologists needed scientific proof that the holes in the rock were genuinely ancient." "Carbon dating could not tell them when the holes themselves were made," "so Tom Scott and Harley Means from the Florida Geological Survey were called in to examine the limestone to determine the circle's age." "The first set of things we looked at were definitely manmade in origin, in that it was an old septic tank that had been put in in the 50s and we noted the marks where the equipment had dug the, the hole for the septic tank" "and then we started looking around at the other features that were presumably of, of older Indian origin." "This shot was taken to demonstrate what Tom and I speculated was probably the best line of evidence for the antiquity of these holes and that is you can see right along here a thin crusty feature." "That's what we call the, the laminated dura crust." "Dura crust shows the age of cut or exposed limestone." "It comes from calcium carbonate in the ground water which rises to the surface when the rock is exposed to air." "The calcium carbonate hardens and over centuries forms a thin, grey layer." "On a section through one of the Miami circle holes the dura crust was clear." "Actually let's talk about this side a little bit." "We have a dura crust that has developed down in the hole." "On top here you can see this surface here and the very thin crust, this is the surface of a limestone and it, the crust was breached when this hole was created and then there was signif, sig, sufficient amount of time for the crust to form here by the" "deposition of calcium carbonate from the water." "It takes hundreds, if not thousands of years, to create these kinds, these thicknesses of dura crust." "By comparing the surface of the rock inside the small holes with the more recent cut surface around the septic tank the difference in age was confirmed." "This is one of the corners of the septic tank right in here and you can clearly see that the saw breached one of these features." "Tom and I also observed dura crust formation around this little feature here, whereas there is no dura crust formation along any of the cut faces associated with this septic tank." "So it was discrepancies like that that led Tom and I to believe that the Miami Circle feature itself was definitely prehistoric." "At last they had proved that the circle was genuinely ancient," "but for the archaeologists there were now many more questions." "All along the Ancient Tequesta had been thought to be nomads moving around to fish and hunt seasonal food, never building permanent homes." "They hunted and foraged in the Everglades, an inhospitable landscape, teeming with alligators and insects." "Twenty miles inland from Miami in the heart of Ancient Tequesta territory, the Everglades are dotted with tree islands, mounds of dry land that sit above the water." "Archaeologist Gary Beiter is excavating a tree island site." "Until they drained the Everglades, the coastal areas here, with canals it was strictly what everybody calls a sea of grass." "It would have been water all around and the only way they could have got around was by canoe and periodically they would want to get some place to sit down and" "sleep, camp site." "Beiter's team is finding a wealth of old animal bones and freshwater shells, evidence of the food the Indians gathered, but there are no signs of dwellings or large structures." "One theory is that they had a seasonal round where they would maybe start on the sea coast at one time of the year," "extract there and then move on into the Everglades maybe in the winter-time and use this as a stopover point on a seasonal round." "This does not look like it was a, a main habitation site." "While the archaeology shows that people stopped and ate here, it seems the mound was merely a temporary refuge for the nomadic Indians as they gathered food." "Sites like this reinforced the view that the Tequesta did not build, so was it really the Tequesta who built the circle?" "There was only one way to be sure: to compare artefacts found at the circle with objects from other sites in the Miami area known to be Tequestan." "Deep in the vaults of the Miami Museum," "Carr tracked down a collection of artefacts from an earlier excavation of a known Tequestan site." "Not surprisingly the most common types of artefacts were made out of shell and bone." "Hard stone or hard rock which is common throughout all of North America outside of Florida simply was not available." "Artefacts found at the Miami circle exactly matched the objects in the museum." "Together they gave a clear picture of the ingenious technology of the Ancient Tequesta." "What a lot of archaeologists thought were ornaments these are drilled shark's teeth but this was no prehistoric version of, of surfing paraphernalia, but rather these were very important tools." "This was part of a knife kit." "They would actually put these shark's teeth into the wooden clubs, or wooden handles, and use them for cutting." "From a stingray barb they could create a very awesome, very powerful little point that when attached to a shaft could do what any other stone artefact could do." "It all added up to strong evidence that the circle was a Tequesta site, but this only deepened the mystery." "What exactly had the Tequesta built here and why?" ".85" "Archaeologist Randolph Widmer was brought in to excavate the area surrounding the circle." ".85" "He started by establishing what the holes were for." "The holes in the ground are the evidence that we have that there was a building or a structure in place." "There had been theories that the holes might be for standing stones or totem poles, but to Widmer it was clear that the holes had once held wooden posts supporting the walls of a building." "We have the circle and we have the outline of it and we kind of have an idea that it really is aboriginal, but what we don't know is how typical it is." "Are there others, is it unique?" "To work out what kind of structure the circle once was he needed to uncover much more of the surrounding site." "These are the features that we're looking for, these circular holes dug into the-- bedrock by the Ancient Tequestans 'cos what we're trying to do is find the holes that actually go into the bedrock," "these larger bases that go into the bedrock and you can see those start to appear as we dig through the, the upper fill." "The more his team dug in the area surrounding the circle the more basins and post holes they found." "I mean what we're finding is there's about one hole every square foot which is a considerable number." "If he could see that the holes formed patterns it might mean that there were other structures beyond the circle, but so far the holes seemed utterly random" "and there was a further puzzle." "One of the things that you, you find as archaeologists when you're excavating structures that are placed on ground level are indications of floors and activities on floors and particularly hearths, or some place where they control the fire and do cooking." "In this area in our excavation we found no evidence that there has been fire on, in the bedrock." "If there was no sign of cooking on the rock surface could it be that people hadn't lived here after all, or could this be a clue to the structure?" "In unravelling these mysteries the archaeologists would shed entirely new light on the Tequesta and their culture." "First, there was another enigma: the two perfect but unused stone axeheads." "They were made of basalt, a volcanic rock, but there's none in Florida." "The Tequesta had made all their tools from shell." "Here you're looking at the perfect example of what an axe would have looked like in any part of the world, but in this case strictly ma, made out of the lip of a conch shell and made so hard and so fine" "that this actually can be used for cutting down trees." "Though shell was versatile, stone is much harder, so these basalt axes would have been very useful, but they had never been used, so where did they come from?" "Geochemist Jackie Dixon, an expert in volcanic rock, was asked to analyse the axes." "Different basaltic lava that are erupted in different types of geologic environments, have very distinct geochemical fingerprints." "We compiled all the data, we got the chemical composition of the hand axe and we compared them to the chemical compositions of hundreds of samples from North America and South America." "Dixon searched through all the samples of volcanic rock structures for an exact match with the axes." "We found that the closest match was to an area around Atlanta, Georgia, Macon, Georgia." "If the tools had come from Macon, Georgia they must have reached the Tequesta in Miami through 1,000 mile network of trade." "The axes must have been so precious that they were never used as tools, but clearly they still had an important function." "They gave it to the Gods, they used these for rituals." "There's no obvious sign of wear or breakage on these axes." "Certainly they were offerings." "In fact we know that one of them had to be an offering." "It was put deliberately into the circular hole." "If these rare objects were placed within the circle as offerings, then perhaps this was a place of religious significance," "so what kind of structure was the circle?" "From what the archaeologists knew of other Indian cultures they thought the circle must have been a very early example of a tribal meeting house." "A good example of one of these buildings has been reconstructed in the north of Florida." "Apalachee Indians built a meeting house here in the 18th century, that is 1700 years after the Miami Circle was built." "The meeting house was a combination, town hall, hotel, church and theatre." "The original building was destroyed long ago, but in 1984 archaeologist Bonnie McEwan and architectural historian Herschel Shepard uncovered its foundations." "We have reconstructed it exactly where we found it archaeologically and so what you see here is what we've been able to verify in the ground, including the depth and diameter of each post, the spatial relationship of all of the elements that you see," "as well as other specialised features - for example, the heath, which we know archaeologically was bout 15ft in diameter." "Unlike the Miami Circle, the San Luis house did not have its post holes cut into bedrock, but the team had historical documents to fill in any archaeological gaps." "The building seems to be laid out in a series of eight concentric circles." "The columns are located on one of those circles very clearly." "And the major support posts are massive and they extend, for the most part, between five and six feet below the ground surface." "And the outer ring and the bench posts seem to be related to the other circles, perhaps even the opening in the roof, so there was obviously a very strict geometric system and pattern working here." "The size of the skylight, which is something we would never recover archaeologically, we know from documents was about one third the size of the total diameter of the building, so this building is just over 120ft in diameter and so the skylight" "would have been approximately 40ft in diameter." "All the features of this building were concentric and precise." "All activity focussed on the hearth, archaeologically distinct in the very centre of the meeting house, but the Miami Circle is different." "The circle is archaeologically unique as its post holes were cut into rock." "It is also 1700 years older than San Luis, but other intriguing features also set it apart." "In the circle there's no central hearth, there's no indication whatsoever of actually burning on the surface of the site." "There is another crucial difference from the regular design of the San Luis house." "We're having a hard time finding any kind of patterns, either rectilinear or curvilinear, circular patterns of these holes to suggest a open interior space using the ground surface" "At San Luis there were geometric patterns marking out the interior," "but not here." "The interior pattern of holes is completely random." "The circle was still a puzzle." "It was most likely a Chief's or meeting house, yet key archaeological details were wrong and it might all have remained a mystery, but then Widmer considered a major factor in Florida:" "the weather." "This site is right on the edge of the Bay and look, if a hurricane comes through with a big tidal surge it will wipe it out." "When he took the weather into account Widmer finally found the answer he was looking for." "He believed the Tequesta had built the circle with a simple but ingenious means for avoiding floodwaters." "The floors are not on ground level, but instead the houses are elevated above the surface of the, of the, of the site of the ground on stilts or pylons." "There is no regular pattern to the interior holes because the posts weren't supporting walls, they were stilts supporting a raised platform floor." "This would explain why there is no sign of a hearth or fire on the rock." "The floor of the house was never on the rock itself." "The structures were on ground surface." "They'd be literally swept away, so by elevating it it gives you some protection from probably a typical, you know, lower intensity hurricane storm." "A building on stilts made perfect sense," "but Widmer was now trying to make sense of another puzzle:" "the complicated arrangement of post holes in the rock, bizarre even for a stilt structure." "What we have in this excavation here, it's one of these large post holes." "One of the more fascinating aspects of our research is that we've uncovered that these post holes occur in multiple groupings and here we have" "1, 2, 3, 4, 5, 6 and actually one down here 7, 7 post holes." "Now the question is why would they do this?" "Why were the posts in clusters side by side?" "After some thought, Widmer came up with a theory." "In a humid climate wooden posts have a limited lifespan." "One of the things that, that I think is going on is once you have the structure up and in place as the timbers rot up you have to continually replace them and to do that what you will do is you'll move" "another timber into position right next to it, alongside of it, as the other post rots away." "This indicates that the structure was still in place and they were trying to constantly shore it up and keep it in operation." "According to Widmer, the building was constantly repaired with new timbers while it was still standing, but the arrangement of holes gave Widmer a vital clue to something more fundamental:" "how long the Tequesta had settled here." "He calculated how long a wooden post could survive in this climate." "If we assume that each one of these timbers lasts approximately 50 years and we have seven timbers in the same spot that would suggest that we're talking about 350 years of having this structure in place, so they've been building" "and rebuilding these structures over that time period." "The Tequesta, this apparently nomadic people, were settled here continuously for at least 350 years." "From Widmer's theories and the San Luis house it is possible to reconstruct what this ancient Tequesta village might have looked like." "The circle was probably a ceremonial meeting house on a raised platform." "The building was supported by large structural posts." "Stilts in the smaller holes within the circle supported the living platform." "The building was probably cone-shaped with an open roof, its sides covered in woven grass." "The smaller multi-family dwellings surrounding the circle also had raised floors, propped up by wooden posts." "The houses probably had sides of woven grass and a sloping roof and their inhabitants cooked on stone slabs on the platform floors, not on the ground itself." "In this way the whole Tequesta village rose up on pilings above the ground framed by the waters of the Miami River and Biscayne Bay." "It is possible that the village was even older than the circle itself." "The remains of shellfish once eaten on the site were carbon dated." "The results were sensational." "The earliest date is 730BC." "This means that the settlement could have been founded 2,700 years ago." "What has been discovered has changed our entire view of the people who once lived here." "In Ancient Miami the Stone Age Tequesta had a thriving, long-term settlement." "Here they had built homes and perhaps much more before the founding of the Roman Republic or the building of the Parthenon in Athens." "What we have just discovered was not only dispelling the myth that the Spanish had created, but I think enlightening all of Miami and Florida that they had a real treasure in our own backyard." "Within two hundred years of Europeans arriving in Florida the Tequesta had disappeared." "War, disease and slavery wiped them out." "They have no known descendants." "but the Miami Circle is their lasting legacy, evidence of a culture as creative and surprising as any in North America."