The St.

Louis suburb of Collinsville, Illinois — which spreads across much of the former Cahokia landscape — was built largely on top of and through the remains of the city, with streets, subdivisions, and commercial development obliterating features that could not be moved.

The preservation of the Cahokia Mounds State Historic Site, which protects the surviving core of the site including Monks Mound and the Grand Plaza, was the result of sustained advocacy by archaeologists and preservationists in the mid-twentieth century.

The site was designated a UNESCO World Heritage Site in 1982 — a designation that recognizes its outstanding universal value and places it alongside monuments like Stonehenge, the Pyramids of Giza, and Machu Picchu in terms of international cultural significance.