Old Bethel Chapel was first built in 1773, though the current building dates to the rebuilding of 1825/6. It is in the simple Gothic style, built from whitewashed rubble stone with a slate roof over. It is a long-wall entry type, with a simple balanced front with a pair of pointed-arched windows in the centre with doorways right and left, and smaller pointed-arched windows to the gallery stairs at either end. The windows have Y-tracery hears with small panes below.
The chapel is an exceptionally well-preserved example, retaining its contemporary furnishings, rendering it one of the last early nineteenth century interiors to survive unaltered in South Wales. It has a stone flagged floor, and flat whitewashed six-bay ceiling with visible soffits of the tie beams. The gallery is supported by cast-iron columns and later supports, which replace original timber peris. The fireplace opposite the pulpit on the long wall has a raised iron fire-basket set flush in a whitewashed brickwork surround.
