Magazine on NW side of Mumbles Lighthouse

The building is a rectangular, single-storey magazine located on the northwest side of Mumbles Lighthouse. It is constructed of reinforced concrete and features a flat roof that is partly covered with turf. On the eastern side, there is a doorway on the right with pintles for double doors, and to the left, there is a window with external strap hinges from former shutters. Both the northern and southern walls have two windows each, also with similar hinges, and one window in the southern wall retains part of a steel shutter. The western wall, which is built against a bank, has four lower-level openings, each with a row of narrow vertical vents above them, some of which are blocked.

The roof is supported by two concrete cross beams, and the floor includes four low concrete bases along with drainage channels.