The Gun Carriage Store, also known as Building 20, is located in Historic Old Québec’s Artillery Park, in the gorge of the St. John Bastion, bordering Rue d’Auteuil. The hangar is a stone building composed of four 14.9 meters (49-foot) sections each with five double doors and a dormer in its centre, and a final 4.8 meters (16-foot) section. The building follows the natural slope of the land and has a stepped profile.