The powder magazine is the best preserved of the original structures at Fort Belknap. The fort, named for its builder, Brig. Gen. W.G. Belknap (1794-1851), was one of the frontier posts placed by the Federal government along a line from the Red River to the Rio Grande to guard settlers from Indians soon after Texas joined the Union. By 1853, this was one of 9 stone and 7 picket houses on the site. It was restored by the State of Texas in 1936.