The U.S. government allocated money for arsenals in 1804, and a year later Benjamin Henry Latrobe and Robert Mills marked the future site of this one on their town survey. The original one-story building, perhaps with arched wagon entrances into the gable ends, housed cannon, grape shot, powder, and supplies. Later, it served as a barracks, cholera hospital, post office, custom house, and railroad office. The Trustees of the Common took over in 1852 and established the New Castle Institute, adding a second story (as seen in the brick-work) and Italianate cupola and changing the fenestration and doorways. It remained a school until 1930. A remodeling moved the spirited cannon-and-eagle bas relief from north gable to south and replaced the cupola with a more Colonial-style one, eliminating, according to a WPA newsletter, the “excrescences of the rococo period of American architecture.” For years, the building has housed a restaurant. A renovation (1999–2001, Bernardon Haber Holloway) replaced the cedar shake roof with terne metal (steel sheets covered with a protective alloy finish).