Located next to the Fire Watchtower is the Military Prison that was built around the same time as the watchtower, between 1823 and 1826. It was used for its intended purpose of holding soldiers who had been arrested up until the 20th century when it was given over to be used as a museum, although it ended up being used as a library and a registry office for a period. Now it holds the Military History Museum and has displays on the Russian Army throughout the ages. The museum is run as part of the Kostroma Historical, Architectural and Art Museum Reserve.