Also known as the Red Tower (due to the colour it was painted and restored in), Grand Master Lascaris built St. Agatha’s Tower in 1647. At the time of its construction, it was the furthest outpost from Valletta and served as a signal post for communication with Gozo. One of the main defensive positions during the time of the Knights, it was equipped with a cannon and garrison of 30 men.
The entrance to the Tower is approached by a flight of steps separated from the door by a drawbridge. Square in plan with four corner towers rising from the base, the outer walls are about four metres thick, through which small windows were cut. In the 18th century, a low star-shaped entrenchment was added.
During the British period the tower was used for defence purposes and was manned during both World wars. In recent times it was equipped as a radar station by the Armed Forces of Malta.