BUILTH or BUILTH WELLS, market town, Brecknock shire, Wales. Population urban district (1931) 1,663. The town is at the focus of the Irf on, Ithon and Wye valleys in a small plain beneath high hills, and as such the region has a marked indi viduality, already noticed by Nennius. Under the Normans the district became a lordship marcher annexed to that of Brecon, but it fell away on the marriage of William de Breos' daughter. At the east end of the town is a fine moat and bailey castle prob ably erected by Bernard de Newmarch, with traces of a later stone castle of Edwardian date. As an advanced outpost of the invaders in the upper Wye valley the castle suffered severely, notably at the hands of Llewellyn ap Gruffydd, prince of Wales, in 1260. In this neighbourhood Llewellyn himself fell in ambush in 1282 and with him collapsed much of the Welsh resistance. The lord ship remained in the Marches until the Act of Union, 1536, when it was grouped with a number of others to form the shire of Brecknock. With the development of better roads in post-medi aeval times Builth became an important gathering centre for west Wales cattle for transport by road to England ; and its fairs and marts, for sheep and ponies, are still well attended. It is a summer resort, visitors being attracted chiefly by the beautiful surround ings, mineral springs and salmon fishing. The town has a station on the old Cambrian (now G.W.R.) line from Moat Lane to Brecon and has been an urban district since 1894. In 1898 the urban district was made conterminous with the civil parish and renamed Builth Wells. It is included for parliamentary purposes in the joint counties of Brecon and Radnor. (See BRECONSHIRE.)