Plas Castell, also known as Castle House

Plas Castell, also known as Castle House, is a large detached townhouse of three storeys with a lower, two-storey service wing adjoining to the north. The main block is of double-pile plan beneath hipped slate roofs. The building is constructed of limestone rubble with sandstone dressings; the east side of the service wing is rendered, and plain red brick Victorian chimneys serve the structure.

The main facade is symmetrical with three bays and presents a formal composition. Three steps lead up to a central porch with engaged Tuscan columns and piers, surmounted by an entablature with dentilated cornice. The porch is topped by a flat roof with stone balustrade featuring square balusters and simple part-glazed double doors. Flanking the entrance are canted ground floor bays with dentilated cornicing and pierced ocular balustrades to flat roofs, fitted with plain sashes. The first floor displays tripartite sandstone windows with segmental central sashes and narrow round-arched flanking sashes; moulded dripstones in the form of cornices run above them, the central group being dentilated. The upper floor has three plain square sashes with moulded sandstone architraves and projecting stone sills; the centre sash is surmounted by a moulded label carried on consoles. Primary moulded cornices run to the rear and sides, whilst the main facade has a 19th-century dentilated cornice. A panelled parapet with a raised central section features relief-carved wreaths and a central heraldic shield.

The south elevation has two canted bays to the ground floor with plain parapets. Above the westernmost bay is a tripartite window as before, with two further square sashes to the second floor; between them is brick quoining to a blocked-up primary window. The rear elevation is asymmetrical with a primary two-storey central projection containing a large Venetian window with plain sandstone surround that functions as a stair light. Originally flanking this were two rectangular windows; that to the left is now blind and that to the right is reduced with a late 19th-century plain sash. Further sashes and a modern window appear below. A 19th-century infill extension to the right features plain sashes with brick quoins and a tall brick boiler chimney.

Adjoining the main block to the right (north) is a two-storey service range with a single-storey rear addition and a central two-stage chimney, the upper stage being of engineering brick. A modern conservatory addition of rubble and timber is extruded in the angle with the main block. To its right is a large tripartite entrance group within a chamfered, depressed-arched opening with a part-glazed central door and plain flanking half-window sections. Beyond this is a deeply recessed entrance with a part-glazed door and rectangular overlight. A large first-floor tripartite window appears to the right, with further sashes of conventional type. The single-storey rear addition to the service range includes an advanced late 19th-century section to the right with a porch featuring a round limestone arch with keystone and a deeply recessed four-panel inner door with rectangular overlight. To the left of this is a large 19th-century Venetian window with plain pediment above. Beyond, in the recessed section, is a further Venetian window of 18th-century date, positioned here in the late 19th century from elsewhere and presumed to have originally come from the principal facade of the main block. A two-storey section adjoins to the far left with plain sash to ground floor and paired sashes to the first floor; a three-stage chimney with laced and oversailing brick upper courses completes this part.

The entrance hall is distinguished by fine plasterwork with a modillion cornice enriched with dentilated and egg-and-dart ornaments. A late 19th-century parquet floor and oak dado panelling are present. Four recessed four-panel Victorian doors open from the hall in panelled Regency architraves with rosette bosses at the corners and panelled reveals. A depressed arch separates the entrance hall from the stair well, supported on enriched plasterwork consoles. The stairwell retains the same modillion cornice and houses a stained glass panel in a 20th-century cupboard arrangement beneath the stair. The staircase is a Victorian replacement of a Regency predecessor, of narrow well type rising to the attic floor, with cast iron decorative pierced flat balusters and a swept mahogany rail that has been reused and adapted.

The Drawing Room features a heavy, enriched plasterwork cornice with egg-and-dart and foliate motifs. The walls are framed out in plaster ribbing with indented corners and rosette motifs. A Victorian figured grey marble fireplace with shouldered arch and mantelpiece supported on consoles is installed. The Dining Room possesses similar plasterwork to the Drawing Room with a shallow ribbed plaster ceiling of conjoined geometrical shapes in the Serlian manner. A wide segmental buffet niche with panelled pilasters and architrave is fitted with plastered dado panels. An oak carved fireplace features paired fluted pilasters with acanthus capitals and bases and a heavy moulded mantelpiece above a gadrooned cornice. The frieze displays a Renaissance-style relief panel.

The principal first floor rooms contain fine fireplaces: one of grey figured marble with a steel grate having bird relief panels; another of bizarre Victorian Baroque design with eclectic carving including swags, wreaths and modillion elements; and in the front-facing left-hand bedroom, an arched fireplace in 19th-century French Rococo style with shell and volute motifs. Recessed six-panel doors throughout feature moulded architraves and panelled reveals.