A motte and bailey castle was built in Brecon in the eleventh century. Only the southern wall of the three-storey Great Hall built in the late thirteenth or early fourtenth century survives. It is pierced by four Early English style, and four lancet windows. Crenellations and arrow loops also survive. The lines of the eastern curtain wall of the castle and the opposite wall of the Great Hall have been uncovered during excavation work. The piers of the hall have been found in the domestic quarters of the hotel which surrounds the courtyard.

The castle site comprises a roughly triangular area, about 130m north-south and 100m across the north, tapering to a blunt point in the south above the confluence of the Usk & Honddu rivers. The Honddu divides the castle from the medieval & later borough to the east (NPRN 32994). The castle precincts are generally defined by banks & scarps, with a motte occupying the north-east angle, topped by the remains of a tower complex, the Ely Tower (NPRN 309157). The ruins of the hall - as desribed above - lie within the southern part of the enclosure. The castle is divided in two by Castle Square, the area to the north , including the motte & Ely Tower, having been laid out as a garden (NPRN 86045), the southern portion, with the hall remains, being occupied by the Castle Inn/Hotel & its grounds (NPRN 25234).

J.Wiles, RCAHMW, 12 July 2004