Builth Wells (/ˈbɪlθ ˈwɛlz/; Welsh: Llanfair-ym-Muallt ⓘ) is a market town and community in the county of Powys and historic county of Brecknockshire (Breconshire), mid Wales, lying at the confluence of rivers Wye and Irfon, in the Welsh (or upper) part of the Wye Valley.

Builth is a longstanding anglicisation of the Old Welsh Buellt or Buallt, which combines bu ([bɨː]) 'ox' and gellt (later gwellt) 'lea or leas'.

The laws of the time suggest that the medieval and later economy of the Welsh borders was strongly dependent on cattle.

Nearby Mynydd Epynt was famous for its horses until it was seized for military training purposes.

Llanelwedd Quarry was the source of the stone used in many of Builth's buildings, and in the dams along the Elan Valley.

[17] The town is served by Builth Road railway station on the Heart of Wales Line, which is located just over 2 miles to the north-west.

One of the main Wales north-south trunk roads, the A483, passes through the town, using the former railway route.

According to a 2010 report by Estyn its rate rose to 77%, making it 9th best performing (state secondary) in Wales and the only ranking in Powys after Llanidloes High School.

[21] The town features Wyeside Arts Centre, which has two cinemas and a live performance stage.

Builth Male Voice Choir has approximately fifty members and performs concerts to support local and national charities.

Builth Wells has a large number of Grade II listed buildings and fixtures.

[24] A plaque on the wall of the post office stakes its claim as the only in England and Wales to bear a contemporary inscription to less-than-one-year monarch Edward VIII.