The Watertown Arsenal was a United States Army facility located in Watertown, Massachusetts. Established in 1816, it played a crucial role in the production and storage of military supplies, including ammunition and weaponry, especially during the Civil War and both World Wars. The arsenal was known for its innovative manufacturing techniques and contributions to military logistics. In 1995, the Watertown Arsenal was officially closed, and the site has since been redeveloped for commercial and residential use. Today, it serves as a reminder of the area's military history while contributing to the local economy through new businesses and housing developments.