Pen-Rhiw farm appears on the first and second editions of the 25-inch Ordnance Survey maps, published in 1888 and 1901. It also appears on modern editions of the Ordnance Survey maps. The first edition shows the farmhouse as a lightning shaped building, with a small building attached at the south west end and a larger rectangular building attached to the north west end. Little had changed by the time the second edition was published, except that two separate additional buildings can be seen to the north east of the main building. Modern editions of the map appears to show the two separate buildings remain, although the main lightning-shaped building now seems to be two attached L-shaped buildings.

Undated photographs by Cadw (ACL 133-01-152) show a two-storey farmhouse with four windows (all four-panes) and steps leading up to a side entrance. Just behind the house there is a stone-built barn with slate roof and wooden doors. Inside the barn, wooden beams and the slate roof remain exposed.

M. Ryder, RCAHMW, 28 March 2023