U.S. Cavalry Museum
The building was built in 1855, originally to serve as the base hospital. In 1890, it became the Cavalry School Administration Building until 1957 when it was repurposed as the Fort Riley Historical Museum. It was renamed the U.S. Cavalry museum in 1962. 
Since the museum is on an active U.S. Army base, there are restrictions on visitors, including requirements for photo identification.