From this investigation it would appear that originally the interior of the ringwork had been defined by an inner rampart and that the contemporary structures were built of wood. At a later date a stone round tower or keep was built at the southern end of the interior of the ringwork .. (details given) .. A stone curtain wall, about 2m wide, was then constructed around the interior, abutting the tower and cutting into the remains of the earlier inner rampart. A D-shaped stone tower was added to eastern and western sides of the curtain wall, and a twin D-shaped towered gateway, also of stone, was constructed at the northern end of the interior. Following a major structural collapse, the gateway was rebuilt to form an enlarged gatehouse, and the adjoining part of the curtain wall to the west was also strengthened .. (some details of finds given) .. It is considered that the ringwork was built in the late C11 or the early C12 and would have been vital in securing the lordship boundary. The subsequent stone-built enclosure castle, comprising the round tower, curtain wall, D-shaped side and gate towers, is believed to have been built in C13, during which time it served as a border outpost for the lordship .. Despite some damage from modern stone quarrying, Castell Bryn Amlwyg is a good example of a ringwork which has been subsequently used to form an enclosure castle. (EH scheduling report 2001)
The modern name, in use locally, is Castle Cefn Fron. Paul Remfry informs Gatehouse this is the probably site of Castle Hithoet mentioned in contemporary documents.