Fairground Park is a municipal park in St. Louis, Missouri, that opened in 1908. It was originally a privately owned facility, used by the St. Louis Agricultural and Mechanical Association for the St. Louis Exposition from 1856 through 1902, though interrupted by the Civil War when the Fairgrounds were used as a Union encampment known as Benton Barracks. The annual exposition ceased in 1902 as preparations for the 1904 World's Fair began. Another blow to the fair's revival after 1904 was the abolition of horse racing in Missouri in 1905.
In 1908, after a protracted political debate, the abandoned 132-acre (0.53 km2) fairground was purchased from the association for park use by St. Louis for $700,000. The park was dedicated on October 9, 1909.
All of the former fair structures and zoo buildings were removed except the bear pits of the old zoo and the amphitheater. In 1912, the amphitheater was removed and replaced by the city's first municipal swimming pool, then said to be the world's largest. This was replaced by a new pool in 1958 as part of the 1955 bond issue program, which also provided lighted ball diamonds and hard surface tennis courts.