Sugarloaf Mound is the sole remaining Mississippian culture

Mississippian culture

The Mississippian culture was a mound-building Native American culture that flourished in what is now the Midwestern, Eastern, and Southeastern United States from approximately 800 CE to 1500 CE, varying regionally....

 platform mound

Platform mound

A platform mound is any earthwork or mound intended to support a structure or activity.-Eastern North America:The indigenous peoples of North America built substructure mounds for well over a thousand years starting in the Archaic period and continuing through the Woodland period...

 in St. Louis, Missouri

St. Louis, Missouri

St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...

. The mound covers three city blocks, measures approximately 40 feet (12.2 m) in height, 100 feet (30.5 m) north/south and 75 feet (22.9 m) east/west. It is located on the former border between St. Louis and the autonomous city of Carondelet. In 1809 the mound was used as a survey landmark when St. Louis was incorporated.

It was purchased by the Osage Nation

Osage Nation

The Osage Nation is a Native American Siouan-language tribe in the United States that originated in the Ohio River valley in present-day Kentucky. After years of war with invading Iroquois, the Osage migrated west of the Mississippi River to their historic lands in present-day Arkansas, Missouri,...

in 2009 in order to preserve it.