Exterior
A large stone mansion, the playful military character of which is mainly due to the alterations and additions made for Sir John Hay Williams by Hansom and Welch, architects, in c1830-1842. The form of the earlier mansion, with its pair of advancing wings, is apparent on the SE side (the main front), but otherwise the composition avoids symmetry. The older part of the house is of 3-storeys but additional parts are of mainly of 2-storeys.
The masonry is in the local limestone, axe-dressed and coursed, with ashlar surrounds to the windows and other features and with a corbelled and crenellated parapet concealing the roofs. There are prominent stone towers concealing chimneys, and part of the north-east elevation features twin towers linked by a high level battlemented arch. The towers have similar parapets. Entrances to the domestic yard feature gates of lattice construction resembling portcullisses, with machicolations above.
The main front facing the park is the SE elevation. This is the only symmetrical part. It is divided into equal thirds, the outer 2 advancing. The outer parts each have a crenellated bay window, a single 12-pane sash window at first floor, and a single 6-pane sash window at second floor. The centre has a 2-storey triagular crenellated projecting window centrally, flanked by 15-pane sash windows, and with 12- and 6-pane winows above. The windows of this elevation have stone surrounds only lightly bonded to the main masonry, suggesting a reduction of window size.
The NE elevation overlooks the village of Bodelwyddan, and is that in which the military character of the architecture is most featured. At left is a possibly C17 figure in an unsophisticated style of carving, standing in a niche, with a Welsh inscription on the base identifying him as Y Gwr Hir; he wears what appears to be a cowl but otherwise non-monastic garb and his face may be intened to appear cadaverous. There are bones said to be immured in this location. Beneath him is a blocked window. To the right of this are twin towers with large loops and oeillets; on the crenellated arch which joins them at parapet level are shields, one carring the cross foxes crest, the other damaged. Within the great arch are 3-storeys of 2 Gothick windows and to the right of the arch 3-storeys of one similar window, recessed. To the right again is a 3-window range of 2-storeys, the central octagonal bay having 3 Gothick windows and flanking similar windows; 3 simpler Gothick windows above. To the right again is the single storey entrance hall with a similar window and the pseudo-portcullis and machicolations of the entrance with its two-storey octagonal towers.
To the S of the main house there is an irregular sequence of walls and towers (now occupied by the Hotel and called the Williams Village) linking the older part with the domestic yard to the W. Much of this additional part is ivy-grown. It is of 2-storeys, with Gothick windows generally under 4-centred arches. It is linked to the wall of the domestic yard with a gateway containing a pair of ''''portcullis'''' gates incorporating a wicket. This was the original main entrance to the Castle. It leads to the small entrance yard containing castellated and buttressed buildings (occupied by the Hotel as part of The Hensroost) which are oriented with the main house.
The main domestic yard extends to the W of the house forming an irregular rectangle of considerable size, adjoining the original entrance and smaller yard. This main domestic yard has buttresses externally regularly spaced along its curtain walls, corner towers of 3-storeys, and a formal entrance at the W side facing one of the gates in the park enclosing wall. The formal entrance has a dummy tower at left and an occupied tower at right, and machicolations over the gates.
Within the domestic yard are buildings now in Hotel occupation, probably predating Hansom''s work, and now much added to and altered. A range of buildings along the S curtain wall from the W corner retains its low pitch hipped roof. An adjacent range to the E (St. David''s Restaurant) retains original stonework at the front (N) including a pedimented Gothick porch. Parallel to these the Elwy Lounge retains 3 large Gothic windows with timber tracery, and to the E of these a range of altered fenestration including 2 small 2-light Tudor style windows which formerly had window bars. This range has a chimney with ribs on 2 faces (similar to cottage chimneys in the village datable to 1856). Another parallel range to the N (now the Hensroost) has 3 similar chimneys, and on its N elevation (facing the car park) signs of 6 former tall round-headed windows, now blocked, the building having been refenestrated.