The esplanade just south of the tower which originally enclosed the whole of La Barcina is now Grand Casemates Square. The Moorish Sea Gate (Puerta del Mar) strengthened by the subsequent Spanish Sea Gate (Puerta de la Atarazana) provided one of the three access gates to La Barcina, the shipbuilding area that is now Grand Casemates Square. The others were the Land Gate (Puerta de Tierra now Landport Gate) and a southern gate, the Barcina Gate, through a wall that no longer exists. Within the esplanade stood a church, roughly behind the galley house. However, no name exists for this small church or chapel referred to by the local historian George Palao, however, Portillo mentions in his writings that on this spot stood the Hermitage of St. Sebastian, very old and probably built by Christians but not the sacristy.1 It was once thought that when this church was pulled down, the highly decorative doorway was preserved and placed at the entrance of what would later become St. Jago’s Barracks, but this theory has now been debunked.
During the early British period the strengthening of the Rock’s fortifications became a military priority. The north of Gibraltar was particularly strategic because of its proximity to the Spanish lines and any land attack would naturally have to be launched from this direction. The large galley house, with its thick 2.5-metre walls was an ideal building in which to store ammunition. It became a Shot House and was so solidly built that it withstood bomb damage inflicted upon this structure during the 13th siege in 1727, at a time when most of the houses of La Barcina were destroyed. By 1753 the original Shot House was flanked by a Shot Pound and a large yard. The area was so devastated that most of it was levelled in 1713, leaving only the shot house, which survived until it was severely damaged and pulled down after the Great Siege. Thomas James describes the clearance operation thus:2
‘There were, in my time, two gardens of great benefit to the garrison: within side of this Land port gate to Water port, is a piece of ground termed the esplanade, with a large store-house, and an enclosed yard for shot and shells: this store house was built by the Moors for their galleys, now possessed by the Ordnance: on this esplanade are some few houses belonging to the inhabitants. In the time of the Spaniards, this spot of ground was laid out into streets, but the houses being in ruins from the bombs thrown by the enemy in 1727, it was thought more advisable to clear the rubbish away, which was done in 1731, to widen that part of the old mole called the bomb battery… ‘