Pyramids in the U.S. [saintcharlesroofing.com]
An interesting article, and I recommend searching Google for details on some of the artifacts found there, which are exquisitely crafted.
However, there's a notable error: "Mound cities in North America date at least a millennia before Cahokia, making them older even than the Egyptian pyramids" - yet, earlier in the article, we're told that Cahokia was settled in around 600AD. The Egyptian pyramids are much older than 400BC, with the Great Pyramid (used as an example because it's the most famous) having already stood for about 2100 years by that point.
You have to refer back to the arstechnica article they cited: "Mound cities are an ancient tradition in North America, going back millennia before Cahokia. The continent's first known earthworks were in Louisiana. The oldest, known as Watson Brake, dates back 5,500 years—centuries before the first Egyptian pyramids were built." The only problem is that the builders of Watson Brake are thought to be hunter-gatherers, so referring to it as a "city" might be kind of tenuous.
30,000 people into 1,000 houses = ~30 people per house , with no electricity , no flush toilets , no running water , no washing machines .
these cities.. had clean sewage in the cities..and great agriculture.. they were far more advanced than you realize.