Cyfarthfa Castle is a large castellated mansion built in 1824-5 for William Crawshay II, the Merthyr ironmaster; the architect was Richard Lugar. It was sold to the local council in 1909 and converted into a museum, art gallery and school (nprn 31777).
The building is rectangular in plan, with almost symmetrical entrance and garden fronts meeting at a large circular corner tower. It is constructed in Pennant sandstone with coursed bull-nosed facings and ashlar dressings; there are crenellated parapets with false machicolation to the towers and weathered stringcourses to the other walls. The interior retains its main suite of state rooms, including a baronial-style entrance hall and neo-classical library, drawing room and dining room, all now used as a museum and art gallery. The extensive grounds include a large ornamental lake which supplemented the water supply to Crawshay's ironworks at Cyfarthfa (nprn 34078).
RCAHMW, 18 June 2008.