The 10 Weirdest, Most Mysterious Ancient Ruins In America

You can imagine how surprised the pilot who found the giant human figures raked into the gravel in 1932 must have been. The largest one is over 170 feet long, making it nearly impossible to recognize unless viewed from above.Their true origin remains unknown, but it is believed that they are prehistoric and possibly ceremonial.

The mysterious markings on this slanted sandstone rock weighing 40 tons have long been the center of controversy. They have been transcribed incorrectly numerous times, and there are several theories concerning who actually made the markings and when. Native Americans, Chinese, and Norse authors have been proposed. It seems like everyone who looks at the inscriptions sees something different.

This park contains the best examples of remnants of Ancestral Puebloan life, including their impressive cliff dwellings - ancient apartments built into alcoves in the canyon walls. These unique structures have fascinated explorers since the late 1800s.

This snake-like mound stretches over 1,300 feet, making it the world's largest serpent effigy. The age of the mound has been the subject of much controversy, with carbon dating pointing to dates around 300 BC and 1000 AD. Researchers have proposed that this was due to later repair of a much earlier structure.

The 80 remaining mounds of Cahokia make up the largest prehistoric construction in North America. Excavation revealed evidence of the ritual sacrifices of hundreds of people, some of whom appeared to be buried alive. Archaeologists have also discovered evidence of a copper workshop and a Woodhenge-like structure.

Astronomers have estimated that the structure goes back to around 1200 AD, but a piece of wood that was carbon dated only went back around 200 years. Still, that does not prove that the structure couldn't be much older. The Medicine Wheel is sacred to local Native People, serving various ceremonial purposes.

You might not associate ancient mysteries with this modern city, but the oldest permanent prehistoric structure in the Eastern United States was actually found right in the middle of downtown Miami in 1998, when an apartment building was demolished to make way for new condominiums. Thus, a battle ensued to preserve the site and keep it in its current location, which ended up costing the state and other groups a pretty penny. Artifacts found at the site led researchers to believe it belonged to the Tequesta Indians and was up to 2,000 years old.

This particular site might not technically belong on this list, but it is definitely mysterious. It is believed the structures were greatly manipulated by the man who owned the site in the 1930s and ran it as a roadside attraction. William Goodwin was convinced that the site was the American equivalent of Stonehenge, so much so that he moved the monoliths to what he believed were their intended or original locations. So far, there's no evidence that the site has any pre-Columbian ties at all.

Poverty Point is possibly the largest network of earthwork constructions in North America from the Archaic period. There are mounds at Poverty Point that are 2,000 to 3,000 years old. Archaeologists debate whether the site was used for a settlement, ceremonies or trading.

This curved piece of soapstone is covered with crowded petroglyphs. It's believed to have served as some kind of map of the surrounding area and still holds spiritual significance for the Cherokee Indians who who lived here before their forced removal.