Fort Belle Fontaine Park has been a St. Louis County Park since 1986. Few are aware that this was the first United States military installation west of the Mississippi River, established in 1805. Lewis and Clark's Corps of Discovery expedition (1804-1806) spent the first night of their expedition on an island opposite Cold Water Creek and their last night two years later at the fort, which had been established in their absence.
Other major expeditions left from this site between 1805 and 1819 to explore the newly acquired Louisiana Territory. Until it was replaced by Jefferson Barracks in 1826, Fort Belle Fontaine was an important gathering place in the wilderness for officers and enlisted men, Native American, French, Spanish and American settlers, trappers and traders, and the local businessmen and farmers who supplied the fort with necessities.
The structures on the site were built during the 1930s by the Work Progress Administration (WPA).