Castellau Congregational Chapel

Castellau Congregational Chapel is a small, Gothic-style building constructed of narrow coursed stone with a slate roof, sandstone dressings, and a plinth. The main fabric dates to 1843, with substantial rebuilding in 1877. The chapel has a gable end entrance and three-window side walls. Four diagonal buttresses with offsets surmounted by tall pinnacles adorn the corners of the building. Tall, pointed arched windows with Y-tracery, two transoms, and hoodmoulds, which include head or foliate bosses, are set into the side walls. The doorway at the south gable end is chamfered, has a pointed-arched head, and contains 20th-century double planked doors, flanked by tall, pointed arched windows. A rectangular stone tablet above the doorway reads "Independent Chapel Castellau, Built AD 1843, Rebuilt AD 1877." Above the tablet, a replaced three-light window with a round head and wooden tracery, including a transom, serves to light the gallery. Head bosses survive to each side of the arch, likely relating to an earlier stepped window. A keyed oculus is in the gable apex and has been boarded over. A string course follows the line of the roof verges and extends around the pinnacles.

The side-wall windows are divided by angle buttresses with offsets that continue to eaves level as pilasters. Decorations of bosses bearing the heads of men and beasts feature along the eaves. A keyed oculus containing a louvre is present in the north gable apex. A lean-to vestry projects to the rear of the building (west). The east side of the vestry has a planked door with an overlight to the left and a two-light window to the right, both under flat heads. The north side of the vestry is rendered, with two 20th-century three-light windows with flat heads.

An entrance vestibule with panelled doors to the left and right opens to the gallery stairs. Canted doorways lead into the chapel and are panelled with geometrical stained glass and late 20th-century frosted glazing between doors. The chapel features a three-sided gallery supported by cast iron columns with small foliate capitals. The wood-panelled gallery front has a band of cast iron openwork bearing a frieze of trefoils with small leaves. Pipe organs, painted white, are mounted above the north ends of the gallery. Pews with panelled backs and carved bench ends are present in the main chapel and gallery. A screen in front of the ground floor pews includes iron openwork mirroring the gallery. An octagonal, panelled pulpit has an upper tier with cast iron circle decoration and dog-leg stairs to either side with turned balusters and square newel posts. Behind the pulpit is a blind moulded plaster archway with pilasters, dentilled capitals, and a trefoiled head with a circle beneath, topped with a triangular hoodmould and fleur-de-lis finial. The arch is flanked by pointed arched windows with Y-tracery, which were external before the vestry was added. A flat-headed doorway to the left of the pulpit leads to the vestry. The ceiling is canted and includes a highly ornate plaster ceiling rose to the centre, in high relief with foliage. Smaller flanking ceiling roses also feature foliate decoration. Pierced louvre openings are present in the canted sections, two to each side. Stained glass in a geometrical design is found in the later west window and in the east window of the vestry.