Reginald's Tower stands at the eastern end of Waterford's quays, where the original Viking city walls met the River Suir. It is Ireland's oldest civic building and the oldest urban structure in the country still in its original use — as a defensive and ceremonial building for the city. The first tower was built by the Vikings shortly after they founded the city in 914 AD; the current structure dates primarily from the twelfth century.
The tower now houses a Viking heritage exhibition, with artefacts recovered from archaeological excavations across the city. The collection is smaller than the Medieval Museum but the context — standing in a Viking-era tower looking at Viking-era objects — gives it an immediacy that display cases in a modern museum can't quite replicate. The views from the tower's upper levels over the River Suir are worth the climb alone.
Reginald's Tower is at Parade Quay, Waterford. It is one of the five Waterford Treasures museums.