Glyn-yr-Hebog is a two storey building with a symmetrical front and buildings in the same range. It has been described as a `Brych' Plan long house, to which a third room has been added by cutting off part of the combined barn and byre. The interior of the house is 17m by 12m, with 1m thick walls of boulder. It has a projecting chimney-stack at the upper end rather than what seems the general practice of building within the gable wall, and this unusual feature may date it as early 18th century. But there is no reason why the North chimney block and stairs plus the poorly built West wall should not represent a 17th century house. Also there are reports that it was formerly a traveling school from 1650. The chimney-block is built of rubble, partly with clay mortar and is offset. It has an inglenook fireplace, plus a spiral stone staircase. The south end (`stable') has a fireplace and there is the outline of an older building. The later house is built of stone and each floor has flagstone flooring. The house underwent alterations with an extension added to the West side of the North end part of the building in 1979.
(Source: NMR Site Files, AJ Parkinson; Brycheiniog 1972, Jones and Smith, 'The Houses of Breconshire', pp. 59-60) .
Ian Archer, RCAHMW, 28th January 2005