Builth Wells 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 part of the Wye Valley. In 2011 it had a population of 2,568.

Until 1974, Brecknockshire, also formerly known as the County of Brecknock, Breconshire, or the County of Brecon, was an administrative county in the south of Wales, later classed as one of the thirteen historic counties of Wales. Named after its county town of Brecon, the county was mountainous and primarily rural.