Glendalough extensive monastic settlement is located in a glacial valley consisting of two lakes (the Upper and Lower Lakes) which explains the Irish place name Gleann dá Locha 'the valley of the two lakes'. The first monastic community probably began with a small hermitage founded by St Kevin (Cóemgen) in the early 7th century but as the monastery became more powerful it extended its imprint throughout the whole valley. Such early Irish monasteries functioned as centres of royal and ecclesiastical power, locations of monastic communities, centres of learning and craft-working, and the focus of trade.
The visible monuments at Glendalough and those detected through remote sensing include stone churches, a stone cathedral, an undecorated high cross, a decorated 'market' cross, a round tower, decorated grave slabs, a unique gateway and the earthen enclosure that defined the central monastic precinct. These monuments date to the 12th century or earlier. Undoubtedly wooden buildings, pathways, churches or habitations, also existed but have left no visible trace. During the 12th-century reform of the Irish church, Glendalough was given the status of a bishopric and this is likely to have led to large-scale stone building. By the 13th century the abbacy and lands of Glendalough had been granted to the archbishop of Dublin.