Miami Circle

The Miami Circle, also known as The Miami River Circle, Brickell Point, or The Miami Circle at Brickell Point Site, is an archaeological site in Downtown Miami, Florida. It consists of a perfect circle measuring 38 feet (11.5m) of 600 postmolds that contain 24 holes or basins cut into the limestone bedrock, on a coastal spit of land, surrounded by a large number of other 'minor' holes. It is the only known evidence of a prehistoric permanent structure cut into the bedrock in the Eastern United States, and considerably predates other known permanent settlements on the East Coast. It is believed to have been the location of a structure, built by the Tequesta (also Tekesta) Indians, in what was possibly their capital. Discovered in 1998, the site is believed to be somewhere between 1700 and 2000 years old. Some scholars have questioned both its age and its authenticity.

• http://en.wikipedia.org/wiki/Miami Circle