PLAZA DE ARMAS - This parade ground was the central focus of military life in San Cristobal, full of the constant daily activity of formations and drills. To the right you can see two circular structures which shielded the water supply from exploding enemy cannon fire. Below this plaza are 4 large underground cisterns. which stored 2,000 tons of water, over 716,000 gallons! Rain was channeled from the upper levels of the fort into the cisterns by a system of pipes and drains. The single story structure with the loggia to the right was the officers' quarters.