Fodor's Expert Review Blackfriars Abbey
Waterford City Historic Sight
While you can't go inside, you can get close to the remains of this genuinely medieval abbey and get a sense of how impressive it once was. This ruined tower belonged to a Dominican abbey that was founded in 1226 and returned to the Crown in 1541 after the dissolution of the monasteries. It was used as a courthouse until Cromwellian forces destroyed most of it in the 17th century.