St. Louis is located at 38°38′53″N 90°12′44″W / 38.648056°N 90.212222°W. The city is built primarily on bluffs and terraces that rise 100–200 feet (30–61 m) above the western banks of the Mississippi River, just south of the Missouri-Mississippi confluence. Much of the area is a fertile and gently rolling prairie that features low hills and broad, shallow valleys. Both the Mississippi River and the Missouri River have cut large valleys with wide flood plains.