This massive fortification stands upon the steep rocky promontory between Rosia and Camp Bay and is visually one of the more impressive of the batteries in Gibraltar with its layers of earlier defence works, possibly dating to medieval times. Evinces its commanding fields of fire which, for centuries, dominated both the seaward and landward approaches to this strategic area. The origin of its name is unknown with its first mention as such being referred to in a 1771 armament list; however, it is possible that the name derived from the adjacent earlier site of the Hermitage of St. John the Baptist [Ermita de San Juan Bautista] with the subsequent anglicanisation of the priest in charge, at the time, for ‘parson’.
The rocky outcrop was part of the Moorish defensive wall and towers, later reinforced by the Spanish engineers that stretched all the way from the Watergate in the North to the Calita de los Remedios (now Camp Bay). It is first recorded in Anton de Wyngaerde’s sketches of Gibraltar dated to 1567 which shows a crenellated wall and watchtower on this site.
These fortifications are shown in bird’s eye view elevations and plans prepared in 1627 by Don Luis Bravo de Acuña which show the tower located to the South of the outcrop overlooking the Calita de los Remedios. Much of these defences were in a dilapidated state by the time the Anglo-Dutch forces captured Gibraltar. Rosia Bay was soon being used as a safe harbour and a battery was placed on the rocky outcrop above to protect the ships watering in this small cove.