A Medieval Metropolis Existed In What’s Now St. Louis, Missouri, Then Mysteriously Disappeared in the 14th Century

In our current epoch of human history, when populations of major cities swell into the tens of millions, an urban center of 30,000 people doesn’t seem very impressive. 1,000 years ago, a city that size was larger than London or Paris, and sat atop what is now East St. Louis.
Source: geneanet