This sturdy granite building is the oldest surviving structure at Fort Trumbull State Park. At the urging of President George Washington, Congress authorized funds to fortify American seaports in 1794. A French engineer, Stephen Rochefontaine, directed the fortification effort in New England. This blockhouse, sometimes called a citadel, was built under the 1794 federal program, when the first Fort Trumbull was repaired and reconfigured. The first Fort Trumbull had been built almost twenty years earlier on and around this site.
The thick stone walls of the blockhouse taper upward and have few openings. Rochefontaine designed the building to be "bomb proof," meaning that exploding shells could not penetrate the walls. He included a magazine, which is a chamber for storing ammunition, in the cellar. Plans called for the building to serve as living quarters for twenty-two soldiers during peacetime and to crowd in fifty men during a war. The building was also intended to serve as a final defensive stronghold if the fort came under attack and all else failed.
Out of all the buildings constructed from Georgia to Maine under the 1794 federal fortification program, this is the only one that still stands today.