During the last period of British occupation (1798–1802) of Menorca, Sir Charles Stuart, the then British governor, ordered Engineer Captain Robert D´Arcy to build some 12 Martello towers along the coast.
These, when added to the three Spanish towers already in place, gave Minorca 15 towers. (wikipedia)
The Spaniards built the tower at alcaufar in 1786.
Click here to see a detailed work about Menorcan Towers, with their location at Google Maps.