The City of Somerville created this small park in 1890 when Nathan Tufts offered the ancient powder house to the city to protect it from encroaching urban subdivision. Begun in the early eighteenth century as a windmill on the edge of the Two Penny Brook Quarry, which furnished the stone for its rubble walls, this cylindrical structure with conical roof was converted to the storage of gunpowder in 1747 by the colonial government. British general Thomas Gage raided the powder house in 1774; thereafter, it served the American Revolutionary forces. In 1822 it became the property of the Tufts family, benefactors of the nearby university. A fieldhouse (1935–1936), added by the Works Progress Administration at the opposite side of the park, echoes the old mill in its use of native stone and the conical form of its tower.