Waterford, a seaport in southeast Ireland, is the country’s oldest city. It was founded by Vikings in 914 A.D., and parts of its ancient walled core remain. Within Reginald’s Tower, a circa-1003 fortification, the Waterford Museum of Treasures displays local archaeological finds. Famed glass manufacturer Waterford Crystal began here in 1783. Today the company’s modern facility near the historic district offers factory tours.