There are many notable churches in the city, including the Cathedral Basilica of St. Louis New Cathedral, a large Roman Catholic cathedral designed in the Byzantine and Romanesque styles. The interior is decorated with lovely mosaics, the largest mosaic collection in the world. The Basilica of St. Louis, King of France, also known as the "Old Cathedral," is the oldest Roman Catholic cathedral west of the Mississippi River. The Old Cathedral is located adjacent to the Jefferson National Expansion Memorial. The Memorial regularly called "the Arch" is arguably the city's best known landmark, as a well as a popular tourist site. The Arch, and the entire Jefferson National Expansion Memorial park, occupy the exact location of the original French village of St. Louis.

Cahokia Mounds, located 8 miles east of St. Louis near Collinsville, Illinois, holds the ruins of a city of the ancient Mississippian aboriginal culture. Similar mounds within St. Louis, gave the city one of its nicknames, "Mound City".
Magic House, a children's hands-on exploration museum, and Worldways Children's Museum, an international children's cultural museum, are both in Kirkwood.