One of the great monastic centres of Early Christian Ireland, its 31-metre-high Round Tower is among the finest examples of its kind. Glendalough is situated in a remote corner of the Wicklow Mountains, 48 kilometres from Dublin.

St. Kevin settled in the valley as a hermit in the 6th century and later established the first monastery. The settlement grew rapidly; Irish monasteries were not merely religions buildings, but also functioned as centers of economic activity.

The Round Tower dates from the early 11th century, an era when marauding Vikings frequently launched raids on Ireland. It functioned as a bell tower, but was also a place of safekeeping for manuscripts, relics, and sacred utensils. While Irish monks used round towers as places of safety when under sudden predatory attack, they were not ideal for this purpose.