Ivar of Waterford was the King of Waterford from 969 until he died in 1,000. Reginald’s Round Tower is named after his son and successor, Ragnall ua Ímair. The original Viking citadel was built as part of a defensive wall in 1003. This 54 foot, stone stronghold replaced it in the late 13th century. This is one of three towers forming Viking Triangle. During its history, it has been a prison and a mint plus been attacked several times. Ireland’s oldest building is now the Waterford Viking Museum. Inside are exhibits about the Norsemen’s occupation including archeological artifacts.