Mountain glen in County Wicklow, Republic of Ireland, situated 16 km/10 mi northwest of the town of Wicklow. Glenealo Stream, a tributary of the Avonmore, runs through Glendalough, and the area is a popular beauty spot, a centre for rock climbing and hill walking. The remains of an early Christian and medieval monastic settlement attract pilgrims.
St Kevin is said to have established a hermitage here in the 6th century, but the surviving monastic ruins are later and date from the 10th century. The earliest remains are Teampall na Skellig (Church of the Rock) on the southern shore of the Upper Lough and the ruins of Reefert Church and St Kevin's cell, also on the Upper Lough. The main site, containing a large group of mainly 12th-century ruins, is situated near the Lower Lough. This takes the form of a monastic ‘city’, an important seat of early learning. The ruins include the gatehouse to the ‘city’, a round tower (31 m/103 ft high), the Romanesque church of Our Lady (the burial site of St Kevin), St Kevin's Church with its round tower and stone roof, and a mortuary chapel known as the Priest's House. The 11th-century cathedral ruins are extensive and there are remains of four other churches on the site, including St Saviour's Priory, which was reconstructed in 1875. There is also an interpretive centre and an extensive graveyard. On the eastern shore of the Upper Lough is a Bronze Age fort.