The Black Castle ruin stands on a rocky promontory over the sea, at the eastern side of the town. There is a fine vantage point for views over the town and the coast of North Wicklow from the ruins. The Vikings were extremely active in the Wicklow Town area from around 795 and in 834 they plundered the Monastery at Glendalough. In the same year they fortified a strategic rocky promonatory at the mouth of the Vartry River in Wicklow town.

A castle was subsequently built now know ...