The Knights of St John concentrated their defences on the Three Cities and Valletta. Up to the 19th century, only the two old capitals – Mdina on Malta and Victoria on Gozo – were fortified, and even their defences were not particularly robust. Farmers on the outskirts of the capitals could shelter within the cities, but villages elsewhere were left to fend for themselves.
Malta had long had watchtowers, but Grand Master Juan de Lascaris-Castellar of the Knights of Malta commissioned five towers from 1637 to 1640; another knight, Grand Master Martin de Redin, subsequently built a string of 13 towers around the perimeters of the islands from 1658 to 1659. These were strong enough to withstand a small attack, but not a long siege. They were positioned so Gozo and Malta could signal to each other – with fire, gunfire and flags – if Turkish invaders were sighted off the coast. The towers still stand today, and range from simple, small watchtowers, to larger mini-fortresses.