The North Bastion, formerly the Balart San Pablo (St. Paul’s Bastion) is part of the Northern Defences of Gibraltar and the most direct line of attack from Spain. The bastion was built over the older Giralda tower, which was originally built in 1309. The Italian Engineer Giovan Giacomo Paleari Fratino was commissioned by Philip II of Spain to improve the defenses of Gibraltar in the 1560s and the building of this bastion was one of his works. .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.
Between 1731 and 1734 the area in front of the land wall, which had been a marsh, was excavated to a depth of 2 feet (0.61 m) lower than lower-water level in the bay. This provided an additional obstacle to any attacker. At the start of the Great Siege of Gibraltar (June 1779 – 7 February 1783), engineers built a “cavalier” (elevated firing platform) for five guns within the north bastion, by then considered a part of the Grand Battery. Two counter mine galleries were built out from the scarp of the moat towards what is now Laguna Estate.
During the British period the North Bastion continued to be heavily armed. In 1859 the following guns are shown as being mounted on the bastion:
- 5 x 32 lbs
- 6 x 24 lbs Carronade
- 2 x 10 inches Mortar
By 1886 we have returns showing the armament was:
- 3 x 32 lbs SB 42-cwt (Garrison Standing)
- 2 x 64/32 lbs RML (Garrison Standing)
- 3 x 32 lbs SB 42-cwt (Garrison Standing)