Glendalough comes from the Irish Gleann Dá Locha which translates to "The valley of the two lakes".
This famous monastery was founded in the 6th century by St. Kevin and grew to become famous as a center of learning throughout Europe. The settlement continued to expand for 600 years and was destroyed in 1398. The surviving buildings date from the 8th and 12th centuries. The most famous is the round tower which is 34m high and 16m in circumference at the base. A cathedral, stone churches and decorated crosses also survived.