The castle stands within a circular dry moat, about 20 m wide and 7 m deep, which is the surviving visible relic of the period of the original ring motte. The plan now consists of a circuit of buildings using the utmost extent of the old platform and encroaching in several places on to the inner slope of the moat. It is entered at the SW across a causeway where there was formerly a drawbridge, between two late-period gate turrets, of which little more than the outer façade remains. There are guardrooms each side with remnants of good quality rooms above.
The passage between the guardrooms leads to an irregularly shaped ward with a deep well. At the left (W) there are remnants of an early circular tower, with a wall about 3 m in thickness surrounding a circular space of about 3.5 m diameter. To the N of this is a remnant of the early curtain wall and the round front of a small defensive turret at the N corner. The Great Hall is at the far side of the ward (NE); it was a first-floor hall, and the undercrofts of the hall and two wings survive. At the S side of the ward there is a domestic and chapel range, including two towers projecting far into the moat and one internal tower projecting into the ward.
The materials generally are local sandstone, hammer-dressed and roughly coursed. A small amount of Caerbwdy stone is used for carvings and for bands of contrasting colour in the later work refacing the entrance turrets. Other freestone is used in places for carvings and dressings. Much of the stonework of the inner face of the chapel and domestic ranges has been quarried away, and also the vaulting of the undercrofts of the same parts; the most impressive surviving structures are the vaults of the Great Hall. No original roofing remains.
The Great Hall, at NE of ward: The building survives well at undercroft level, but only fragments of the walls above remain. The main undercroft is about 7 by 24 m, spanned by a vault with a rise of about 4 m. This was a plain barrel vault without ribs. The kitchen cross wing at the left of the hall is about 5 by 12 m and the solar cross wing at the right is about 7 by 12 m, both undercrofts also vaulted. The main undercroft communicates only with the latter. The side of the great hall and its wings facing the ward is all in one plane, the projections of the cross wings being to the rear, boldly overhanging the moat. The kitchen part is identifed by rubbish chutes from both the undercroft and the main storey, discharging into the moat. There is also a front extension to it of later date, now surviving only as low walls, with traces of ovens. The other, solar, wing has large windows overlooking the moat. In the front elevation to the ward there was a principal doorway to the left of the main undercroft and two small windows, one well preserved. The main entrance was by external stairs to a door over the undercroft door, but the arrangement was altered as there are signs of a staircase roof cutting across one of the main hall windows. There are no openings at undercroft level facing the moat. One corbel on the SE gable of the hall was evidently a roof support for the solar.
The surviving main undercroft doorway is chamfered and of three orders. There are bulbous stops of an unusual type, at differing levels. There is a rebate for the door, and there are traces of the iron hinge pins in the wall. Slots for door bars are present. The better-surviving window is small and trefoil-headed. A door at left gave access to the kitchen from the ward, but became an internal door when the later bakehouse was added. This doorway has chamfered reveals with broach stops.
The Chapel and Domestic Range, at S of the Ward: A long range of buildings, mainly domestic in character, but including the chapel at the E end. The two towers overlooking the moat are octagonal, the W tower externally only but the E tower both externally and internally. The porch tower facing the ward is square and of five storeys, and is carried up above roof level to serve as a lookout. The chapel was entered from the first floor of the porch tower.
Only the outer wall of the chapel remains, in which there are three deep-set windows with scoinson arches. Two are under a single arch, within what appears to have been a cross-vaulted part of the roof, showing the chapel roof was T shaped or cruciform. The window tracery is carved in Caerbwdy stone. Beneath the chapel are traces of a vaulted undercroft, entered by a side door in the porch and a passage beneath the main stairs. Off this undercroft, in the E octagonal tower, is a dungeon with latrine and beneath its floor an oubliette. At the level of the chapel is a tower room octagonally vaulted, with fireplace, also with a latrine. Above this is another room reached by spiral stairs from the chapel, also with latrine, and with an octagonally groined vault. This room has a separate closet or small bedchamber and was presumably a chaplain's room.
The remainder of the range is domestic in character. Only the outer wall survives to any great extent. There are the springings of an undercroft, and in the main rooms there are fireplaces and windows with window seats. In the top storey there are small trefoil-headed windows. The other tower serves these rooms, containing latrines and closets or small bedchambers. This tower is slightly battered at the base, with some loopholes or narrow windows with trefoiled heads.
The five-storey porch facing the ward contains remains of very awkwardly planned broad winding stairs to the chapel level. The first floor of the porch consists of an antechamber to the chapel, with corner colonettes and traces of cross-vaulting, plus a good doorway to the chapel. From this level the stairs continue in a side projection of the tower, so the upper rooms were rooms and not merely landings; the floors, however, do not survive. At the front to the ward the main entrance to this tower has a label mould with king and queen's head stops. There is a pair of cinquefoil headed lights above.
Entrance Gateway and Towers: The construction is of perhaps three periods, part of the original curtain wall, part contemporary with the main domestic range, but the main front of the time of Bishop Houghton in the late C14. Twin towers with spurs, with a thin arch linking them at high level. At the top are windows with mullions and transoms and there are decorative bands of Caerbwdy stone. Only the base of the corbelled parapet remains, with machicolations at the centre. Behind the facade are portcullis slots. There are guardrooms each side and vaulted domestic rooms above.