Cahokia mound. From sacred destinations.com
Best known for large, man-made earthen structures, the city of Cahokia was inhabited from about A.D. 700 to 1400. Built by ancient peoples known as the Mound Builders, Cahokia's original population was thought to have been only about 1,000 until about the 11th century when it expanded to tens of thousands.
From the article by Tim de Chant, for ¨Per Square Mile¨, I´ve learnt about the ancient city of Cahokia. Read a paragraph and keep on reading:
Cahokia is one of the largest historical American cities you’ve probably never heard of. Peaking around 1250 CE, Cahokia is considered the first Mississipian settlement, a culture which spread to throughout the central and southeastern United States. The city’s inhabitants built over 100 mounds, eighty of which remain. One of them still towers 92 feet over the surrounding fields and is easily visible from the scratched postage-stamp windows of St. Louis’ Gateway Arch. With somewhere between 10,000 to 15,000 people, it held the record for the largest American city until around 1800, when Philadelphia finally overtook it.
With that many people crammed into just under three-quarters of a square mile—the estimated size of the city’s neighborhoods—it may sound like Cahokia was as cramped as the slums of Upton Sinclair’s Chicago. But it probably didn’t feel that way. Sweeping plazas and towering mounds added nearly three square miles of open space, keeping much of the city open and airy like Baron Haussmann’s Paris. Yet unlike the city on the Seine’s astronomical modern density of 58,890 people per square mile, Cahokia’s population lived at a positively suburban 1,000 to 1,500 people per square mile, thanks to the plazas and mounds.
After a summer of intense excavation, Dr. Warren Wittry was studying excavation maps when he observed that numerous large oval-shaped pits seemed to be arranged in arcs of circles. He theorized that posts set in these pits lined up with the rising sun at certain times of the year, serving as a calendar, which he called WOODHENGE. After further excavations by Wittry and other archaeologists, more post pits were found where predicted, and evidence that there were as many as five Woodhenges at this location. These calendars had been built over a period of 200 years (A.D. 900-1100). Fragments of wood remaining in some of the post pits revealed red cedar had been used for the posts, a sacred wood.