The imposing brick mansion of Plas Gwyn (NPRN 15812) was completed in 1754 on the site of an earlier, possibly sixteenth century house. The park around it may be contemporary with the house although in its present form it owes much to the nineteenth century. It is depicted on the Ordnance Survey first-edition 25-inch map, Anglesey XIV.10 (1889).

The park is roughly triangular in shape, fanning out south-east from the village of Pentraeth. The western part of the park is a barren, heathy, rocky ridge falling away to a narrow point at the village below, between the Bangor and Beaumaris roads. The house stands in a green vale at its centre, beneath the woods that clothe its rising eastern boundary. Mixed deciduous trees have been planted in groups in the lower, more sheltered places, and others are dotted across the open parkland. North of the house is deciduous woodland and within it is an icehouse (310109). Terrain rises towards the east and, as the slope becomes steeper, it is crowned with more woods. Further east the parkland is gentler and greener. Specimen trees have survived well so that the park has retained its original appearance. It is still grazed by sheep.

There are two main drives, neither holding to its original route: from the south (Bangor to Amlwch road); and from the east (Beaumaris road). The south drive, the older of the two, runs from an entrance with lodge and ornamental gates (310100-11). It follows a north-east line looping round to the north front of the house, redirected from its original zig-zag route in 1840. The east drive, now disused, runs from the Beaumaris road at an entrance also with lodge and ornamental gates (310113-4). It follows a line west to meet the south drive on the north edge of the lawn. A rear drive from further west on the Beaumaris road serviced the farm.

Gardens lie east of the house (265411), to the south a walled garden (310108), and  the Three Leaps stones rest in a nearby field (302547).

Source: Cadw 1998: Register of Parks and Gardens of Special Historic Interest in Wales: Conwy, Gwynedd & the Isle of Anglesey, 28-32 (ref: PGW(Gd)47(ANG)).

David Leighton & John Wiles, 10 February 2022