town and resort, Powys county, historic county of Radnorshire (Sir Faesyfed), Wales. It developed as a spa, based on medicinal waters first discovered about 1696, and with the coming of the railroad in the 19th century it became widely popular. The spa declined after World War II and closed in the 1960s, but it reopened in 1983. The town is an active tourist centre, with a number of hotels, spacious streets, parks, museums, and a 14-acre (6-hectare) boating lake. It is the administrative centre of Powys county. To the northwest lie the remains of the Roman fort of Castell Collen. Pop. (2001) 5,024.