Aberglanhirin is an upland farm with its farmhouse and outbuildings situated on the southern side of the upper Elan valley. It has historically been part of the Cwm Elan Estate and remains under the ownership of the Welsh Water Elan Estate. The present house is a 20th century bungalow, with the 19th century farmhouse now used as an outbuilding, part of an L-shaped range which also includes a stable, two-bay threshing barn and a cow house. The second edition 1:10560 Ordnance Survey map of 1903 shows that some small additions were made to this range by the early 20th century, and another outbuilding was built to the east. This latter building has been largely demolished, although the lower portions of its walls are maintained as a fold or enclosure at the edge of the farmyard. The main building range survives in good condition and is used for agricultural purposes.

It is likely that this L-shaped range dates to the second-half of the 19th century and replaced or incorporated an earlier building or buildings. Two buildings are depicted on the 1833 1 inch to 1 mile Ordnance Survey map, but neither building is L-shaped. It should be noted that the large field enclosure attached to Aberglanhirin (NPRN 502605) is shown on the 1833 map.

Little is known of the early history of the farmstead. The earliest known documentary references to Aberglanhirin include the will of Thomas Pugh of Aberglanhirin, written in 1802. Pugh died in 1808 and left a relatively valuable estate worth £1378 to his children, including cattle, horses and sheep, some of the latter noted as being depastured on Moelcrychion and Bryn Suog, to the north of the Elan river.

J.J. Hall, Trysor, 17 October 2009.