Building 121, the central power plant, was constructed in 1918.
The Mare Island Naval Shipyard was the first US Navy Base on the West Coast. The land was purchased in 1853 and shipbuilding was commenced in 1854. During WWI and WWII, the base was responsible for the construction of dozens of ships, including destroyers, battleships and submarines. The base closed in 1996 as part of the Base Realignment and Closure Program.