The Mississippian Culture was a North American Native American culture from about 700 AD. Rements of it lasted until the French explorations and settlement of the lower Mississippi. The culture had a trading area from the Appalachians to the Rockies and from Wisconsin to the Gulf.
My first experience with remnants of the Mississippian culture was the Cahokia Mounds complex just outside East St. Louis. You can not really call the man-made hills east of St. Louis "mounds." They are too big for that. The really are "earth works." This city would have been as impressive as Machu Picchu if the building material had been stone. But it was built what was available locally. In Machu Picchu, the local building material was stone. In the central part of North America, the building material was with wood, straw, mud and earth. The only remaining structures are the earthworks. The 70 earthworks that are remaining are massive.
Monks Mound (named after the French monks who lived there in the early 1800s), the largest mound--and probably the most culturally significant--covers 14 acres and rises to a height of 100 feet. It is on a large flat plain east of St. Louis. It is the largest structure around. After climbing the (modern) steps to the top, you can see all the way to St. Louis on the other side of the Mississippi and to the bluffs beyond St. Louis. Chahokia was abandoned around the 1300s .
I also spent some time at the remains of the Grand Village of the Natchez Tribe (of course in Natchez, MS.). They appear to be the last remnant of the Mississippian culture. The remains of the Grand Village of the Natchez Indians is in suburban Natchez, MS, at the end of a subdivision road. It appears that the Natchez were still practicing the ceremonies of the Mississippian culture when the French set up a small settlement in the area in the early 1600s so there are some written descriptions of the practicing culture.
Emerald Mound is just outside of Natchez. The theory is that it was the ceremonial center of the Natchez. It is the largest earthwork in the area and the top has topography similar to that of Monks Mound outside of St. Louis.