Rhowniar is a house of c.1911 by Oswald Milne (1881-1968), architect, a pupil of Blomfield, and assistant to Lutyens. It has two storeys, rendered walls (with first floor slightly recessed), and a slate roof laid to diminishing courses. There is a two storey gabled porch flanked by projecting chimneys with twin stacks. The main front faces the garden, each end has a large projecting gabled block. Between large gables, the centre block has two small dormers with slate-hung gables and two windows set at the eaves. To the right there is a lower conservatory block. The roof sweeps down to the first floor level. There is attached a modern accommodation block for the outward Bound Centre. Internally, rooms to the front have oak panelling and some simple plasterwork and fireplaces. On the first floor, the 'Blue Room' has a barrel-vaulted ceiling.

Reference: Cadw listed buildings database.
RCAHMW, 2009.