The North Bastion, formerly the Baluarte San Pablo (St. Paul's Bastion) was part of the fortifications of Gibraltar, in the north of the peninsula, protecting the town against attack from the mainland of Spain. The bastion was based on the older Giralda tower, built in 1309. The bastion, with a mole that extended into the Bay of Gibraltar to the west and a curtain wall stretching to the Rock of Gibraltar on its east, was a key element in the defenses of the peninsula. After the British took Gibraltar in 1704 they further strengthened these fortifications, flooding the land in front and turning the curtain wall into the Grand Battery.