Ballyhack Castle is located on a steep slope in a commanding position overlooking Waterford estuary. The castle, a large tower house, is thought to have been built c. 1450 by the Knights Hospitallers of St. John, one of the two great military orders founded at the beginning of the 12th century at the time of the Crusades. As this site is managed by the OPW, school tour visits are permitted free of charge provided certain conditions are met.