Llanddew Bishop's Palace is a medieval quadrilateral fortified residence, founded by the bishops of St Davids. Encased by the remains of its irregular 12th century precinct wall, flanked by a small solid half-round bastion, it was built on the site of an earlier Celtic clas or religious community. Adjoining the bastion is the vaulted double-sided Bishop Gower's Well, which is said to be of mid 14th century construction. To the south is a reset doorway, which retains elements of the medieval gate and to the north are the remains of substantial masonry buildings, which include a first floor hall block set over a vaulted basement. The late 12th century home of the archdeacon of Brecon, Giraldus Cambrensis or Gerald of Wales, the site was abandoned after the mid 16th century Reformation but in 1857 it was redeveloped as a vicarage. 2 miles south-east is Alexanderstone Castle and 2 miles south-west is Brecon Castle.