The Gilman Garrison House is a rare surviving example of a First Period garrison house, built with a number of clearly defense-related features. Built in 1709 by Councillor John Gilman, a proprietor of sawmills and member of a prominent family involved in shipping, the 2 1/2-story T-shaped structure with a gabled roof and clapboarded exterior is located at 12 Water Street in Exeter, New Hampshire. It stands near the eastern end of Exeter's historic waterfront commercial district. Today, it is owned by Historic New England, which operates the home as a house museum. It was listed on the National Register of Historic Places in 1976. In constructing his home, Gilman fortified it for protection. The oldest portion has a frame of oak timbers with heaving wooden planking forming its walls. The upper floor projects over the ground floor and there is evidence that the overhang originally had firing portholes in its floor. There also are wall structures indicating that part of the house could be isolated by means of a wooden portcullis.