Located in the grounds of St Columba's church, this tower was built in the 10th century as part of the early Christian monastery. Such towers were used as lookout towers and as places of refuge during attack, particularly from Norse invaders. It is ninety feet high from the original street level to the base of its roof and has six floors but no internal staircase. Access to the upper floors was by way of ladders. Each floor has one window. The raised doorway strengthened the structure and made the tower more difficult to attack. It has a number of unusual features including five top windows instead of the usual four. These overlook the five ancient roads leading into town and correspond to the five medieval town gates - Canon, Carrick, Maudlin, Dublin and Farrell Gates. Reference: http://www.hmdb.org/marker.asp?marker=26440