Capel Mawr (Jerusalem Welsh Presbyterian Chapel) with attached school room

Capel Mawr, also known as Jerusalem Welsh Presbyterian Chapel, is a chapel constructed from roughly coursed rubble with a slate roof featuring red tile cresting. The attached school room is made of brick. The main entrance is located in the gable facing the street, which has a pedimented gable with an inscribed stone at the apex. It features paired four-panelled doors with leaded overlights set within moulded architraves in a Tuscan portico porch, flanked by round-arched windows. Above, there are three similar windows with keystones at the heads. The return elevations have four bays with camber-headed windows on the ground floor and round-arched windows with stressed keystones above, all of which are small-paned with margin lights. At the rear gable wall, there is a later brick projection that houses the organ, flanked by high-set round-arched windows. The chapel connects to the school room on its left through a hipped-roofed entrance block, which includes a gabled porch flanked by three-light mullioned and transomed windows. The school room consists of a single-storey hall with five bays, articulated by buttresses, and features blue brick impost bands linking the round-arched windows, along with a gabled porch on the inner face.

Inside, the chapel has a wide space with a slightly inclined floor, two off-centre aisles, and a canted gallery around three sides. The gallery has a panelled balustrade and is supported by cast-iron columns with Corinthian capitals. The plaster ceiling is divided into panels and includes rosettes for light fittings and vents. There is a coloured glass window from the entrance lobby into the chapel. Wrought metal scrolled posts support a moulded rail enclosing the set fawr, and the pulpit is trefoiled and panelled with curved stairs on either side featuring turned baluster rails. The organ is situated in an arched recess at the rear. Other fittings include grained wood seating and a wood low relief war memorial tablet, as well as a pictorial stained glass window from 1927 by Jones and Wallis. The remaining windows have coloured glass margin lights. A corridor with a deacons' meeting room connects the chapel to the school room, which is a hall of five bays with a glazed brick dado and timber roof trusses, divided by a moveable screen from a smaller room at the rear.