Aberystwyth, town, Ceredigion District, Dyfed, central Wales, at the mouth of the Ystwyth and Rheidol rivers, on Cardigan Bay. A seaside resort and educational center, Aberystwyth is the seat of the University College of Wales (1872), the oldest college of the University of Wales (1893). Also here are the National Library of Wales (chartered 1907) and the remains of a 13th-century castle. Aberystwyth grew around a Norman castle founded in 1277. Population 11,154 (1991).
