1. Circa 1600, altered 17th c. Stepped gables, 2 storey. Rubble. Large quoin stones. Tall square end chimneys. Interior. Stone stair at corner of wide fireplace. Beams. Trusses.
2. A two storey, rubble-built house, clasped by large quoins, thought to have been built, c.1600. The upper part of the walls, together with the stepped gables, are later 17th c. ammendments. There are later alterations, a kitchen added on the W appears (from Os Landline) to be derelict.
(source Os495card; SH33NE16)
J.Wiles 13.03.03

[Additional:]

Plas Gwyn is an architecturally distinguished house listed grade II* as a `particularly important? building of `more than special interest?. The stepped gables give the house an air of distinction which is matched internally by the unusually high ceilings. Plas Gwyn means White House/Mansion, of course, and it was probably so named because it was covered in white render; traces of which survive under the moulded eaves course. Plas Gwyn is described in the Royal Commission's Caernarvonshire Inventory, Vol III: West (1964), pp. 12-13, mon. 1484. The Commission interpreted Plas Gwyn as having two principal phases: (1) a storeyed house of c. 1600, but (2) modified in the first half of the C17th when the roof was raised and the stepped gables added. The opportunity was taken to re-examine the house in July 2016 when the house was empty and some previously hidden architectural features exposed.

Plas Gwyn is a gentry house of Snowdonian plan-type but enhanced with status-enhancing detail, including the unusually high ceilings and the stepped gables. There is no real evidence that the roof has been raised and the stepped gables added, as the Inventory suggests. The stepped gables, `kneelers?, tall chimneys, eaves? course, and quoining all relate well together. The Inventory proposes a building date of c. 1600. This is about right. The house presumably dates from after c. 1580 when Plas Mawr, Conwy, set the fashion in the region for stepped gables. The voussoirs of the doorway are a characteristic feature of the Snowdonian house but the last dated example is at Llwyn-du (1581). The absence of cusping in the roof points to a date after 1578 (when the cusping at Plas Mawr was concealed by a plaster ceiling). All-in-all Plas Gwyn is a most significant house that can be reasonably closely dated to 1580-1600, and is essentially a Snowdonian house with status-enhancing `frills?. Plas Du (Llanarmon) provides a good comparison with Plas Gwyn. It is somewhat earlier and has cusping in the roof but lacks the high ceilings and stepped gables (Caernarvonshire Inventory II (1960), pp. 113-14).
In a second C19th phase, Plas Gwyn, then part of the Broom Hall estate, was converted to a conventional farmhouse plan. The twin outer rooms were converted into a large, heated parlour. A stair was constructed in the passage, superseding the stone stair, and the passage was fully screened. New service-rooms were added: a back kitchen on the W side of the hall and a dairy against the E gable end.
Plas Gwyn was originally free standing and the house stands apart from the farmbuildings. The estate-built farm buildings were constructed from large stone blocks in the C19th. A stone dated 1846 with the initials O.J./ P[las] G[wyn]was recently discovered by Jim Ellis set into the gable end of the farmbuilding nearest the house and seems to be a memorial to an animal (pet dog?) aged 11. R.F. Suggett/RCAHMW/July 2016.

[Additional:]

See now the Report on an Archaeological Watching Brief by I. P. Brooks (EAS Client Report 2017/04). RFS/RCAHMW/June 2017.