Twrgwyn Welsh Presbyterian Chapel

Two-storey, 3-window stepped front with central bay advanced under bracket pediment. Snecked rubble with Penmon dressings including quoins (to ends and centre), first floor cill band, plinth, etc; cornices to both floors and closed balustraded parapets to outer bays. Slate roofs. Sash windows to first floor with balustraded aprons. Tripartite main central window with entablature, cornice and advanced segmental pediment; flanking windows are arched headed. Deep entablature to ground floor centre with paired and pilasters. Arched headed niches with keystones to either side of advanced main entrance flanked by Tuscan columns; panelled double doors. Deep bracketed cornices to outer windows with architraves.

Pebbledash side elevations with sash windows, arched headed to first floor, contained within giant order architraves. Single storey extension to rear right and taller 5-bay hall at right angles behind that with similar arched headed sash windows.

The burial ground is bounded by a rubble wall to front and right side with railings and gate piers with pyramidal caps; much taller to rear.

Rectangular galleried interior with classical detail. Unusual plaster ceiling containing bosses, ribs and central rose, etc, contained within an elongated octagonal border; panelled frieze. The raked gallery with panelled front was inserted at the same time as the front and is carried on cast iron columns. The arched opening into the organ chamber is framed by fluted pilasters, etc. Panelled great seat with foliage trails to brass railings. Staircases with turned newels rise up to either end of lobby. Hall to rear has complicated roof structure with boarded ceiling and patterned ventilators.