Calfaria Welsh Calvinistic Chapel and bordering railings, gates and piers

The building is a Welsh Calvinistic Chapel constructed from rock-faced sandstone with ashlar dressings and a Welsh slate roof. It dates to the 18th century and is situated on Porth Street.

The main facade, a two-storey gable, faces Porth Street. It is regularly coursed and features a five-window arrangement at the first floor. The two outer windows are segmental arched with margin-glazed sashes and incorporate coloured glass, sills, and a continuous hood mould with a keystone. The central three windows are similar, but narrower, with round arched tops, circular upper lights, and incorporating coloured glass. Above the windows is a platband, followed by two small round-headed windows with replaced glazing. Flanking these are two keyed louvred oculi, with a circular inscription plaque at the gable apex and a billet eaves moulding topped with a terra cotta finial. The ground floor has two pairs of segmental arched margin-glazed sash windows, including coloured glass, with an impost band either side of a central doorway bay. This bay projects forward and is constructed of tooled ashlar with a round arch containing voussoirs, a keystone, and a moulded impost band. It contains double six-panelled doors with coloured glass divided overlight and an inscription panel above.

The north elevation (North Road) is three storeys high, including a basement, and is three bays long. It features round-headed margin-glazed sash windows with ashlar voussoirs, keystones, quoins, sills and blocked to the east. Four decorative inscription panels are positioned above the plinth, with coursed rubble below.

The chapel is bordered on two sides by a low stone wall with decorative metal railings and rock-faced piers. The piers flanking the entrance gates have pyramidal capstones.

The interior is in a classical style. A vestibule features a ten-pane coloured glass window and decorative six-panelled doors. Two doors lead to gallery stairs, and two lead to the main interior, which is dominated by a large organ installed in 1900 by Conacher and Co of Huddersfield. This features a richly carved and polished case incorporating decorative painted pipework, set in a high basket arched moulded plaster recess. This recess comprises fluted piers with decorative capitals and a moulded entablature with keystone. In front of the organ is a richly carved and panelled pulpit and set fawr with moulded wooden stairs and brass lights on either side, accompanied by a richly moulded communion rail. The floor is boarded. Four fluted cast iron piers with Corinthian capitals support the raked, three-sided gallery with panelled pews and a moulded panelled front, featuring a central clock. The ceiling has a moulded cornice and decorative boarded panels incorporating six ventilators (one large central and two smaller decorative moulded roses). A Sunday School and further meeting rooms are located to the rear and below.