The military importance of the port of Mahón has been very evident for centuries, especially since the 16th century, when political conditions made it a maritime scale of the link between the Crown of Spain and its Italian possessions. Then, during the British rule of Menorca, it was the port of support of the English squadron of the Mediterranean to become, finally in the nineteenth century, the crossroads of the French route Toulon-Algiers with the English Mediterranean route from Gibraltar to Malta.

St. Philip’s Castle, laid out by J.B. Calvi in ​​1555, was extended several times in the Spanish period (1555- 1708), and with the arrival of the English in 1708 was reinforced with a series of works that formed a double defense enclosure, and also raised the Marlborough Fort, on the south side of Cala Sant Esteve.