The most famous of all the landmarks in Glendalough is the Round Tower which stands 33 meters above the ground. It was built almost 1000 years ago by the monks of St. Kevin’s monastery. The conical roof had to be replaced in 1876 when it was struck by lightning. The towers were called “Cloigtheach”, meaning bell tower, suggesting their main use. The towers were sometimes used as a place of refuge for monks when the monastery was under attack. They also served as both as lookout posts and as beacons foe approaching monks and pilgrims.