Preserving the remains of an ancient Native American city near Collinsville, Illinois, the Cahokia Mounds State Historic Site is across the Mississippi River from St. Louis, Missouri. Covering more than 2,000 acres, Cahokia is the most sophisticated prehistoric Native civilization north of Mexico. Best known for large, man-made earthen structures, the city of Cahokia was inhabited from about A.D. 700 to 1400. Built by ancient peoples known as the Mound Builders, Cahokia's original population was thought to have been only about 1,000 until about the 11th century when it expanded to tens of thousands.
The Katy Trail State Park is one of the nation's longest rail-trail projects-nearly 238 miles of scenic trail built especially for walkers and cyclists and stretching from Clinton east to Machens, in St. Charles County. Equestrians are allowed to use the western section from the state fairgrounds in Sedalia to Calhoun only. The trail occupies a segment of rail corridor that once carried trains of the Missouri-Kansas-Texas Railroad (a.k.a., the Katy). In 1986 the railroad ceased operations along this route, paving the way to creating the extraordinary recreational opportunity it is today. The Katy Trail passes through some of Missouri's most scenic areas. In particular, much of the trail follows the mighty Missouri River, which feature amazing bluffs. In fact, the segment that passes between St. Charles and Boonville is an official portion of the Lewis and Clark National Historic Trail. The trail includes other landscapes as well, such as forests, wetlands, valleys, remnant prairies and rolling farm fields. Despite the changes in landscape, the Katy Trail is relatively flat.