The Red Barn is the only remnant of the Calaveras County Hospital that remains on these grounds. The two-story hospital was built in 1870 and remained in use until Mark Twain Hospital was constructed in 1951. This building served as the hospital's dairy barn, and county documents show that it received major improvements in 1923, including the distinctive red paint. After the hospital closed, the barn was used by the sheriff's posse and the county. In 2004, through the vision and hard work of countless volunteers, the Calaveras County Historical Society restored the dairy barn and opened the Red Barn Museum to the public, sharing the rich history of Calaveras County.