Rhiwlas Hall, a twentieth-century house on a more ancient site (nprn 28709), is located within a small but well-preserved landscape park on the east bank of the Afon Tryweryn. The park lies mainly to the south, west and north-west of the house. The date of the park is uncertain but a late eighteenth-century tourist report indicates that parkland improvements were then under way by the designer William Emes.

The Afon Tryweryn defines the west and south sides of the park and runs all along the west side of the main drive. This long drive, still passable by vehicles but no longer used, leads off from the south-east corner of the park, at Bala, through a grand, castellated, Gothic gateway with lodge on the A494. It passes through a narrow strip of woodland of mainly deciduous trees, with some notable specimen trees, particularly beech and oak. The east, service, drive is now the main approach. The park otherwise falls into two main areas; to the south/south-west and north-west of the house. The park south of the house falls gently towards the river. The house, which faces south, thus looks out towards the river over sloping pastureland, dotted with trees, mostly oak, beech, sycamore and lime.
To the north-west the parkland is of very different character with rocky outcrops on land rising above the house. It was formerly wooded and is still known as Coed Mawr with the character of open woodland. It contains small estate quarries and a network of now disused pathways, including paths leading in a loop along part of the west side and back to the house and gardens, presumably a pleasure walk.

Other features, still faintly visible, included an area immediately south of the house formerly fenced off and mown, with a possible croquet lawn and a small plantation at its south-west corner, and a long bank or terrace running east-west above this, possibly an old fence line. A tennis court has been constructed near the start of the main drive.
An ice-house is located beside the river, and upstream was a series of collecting pools. 
A ha-ha between the garden and park was built in the 1970s, and a tennis court has been constructed near the start of the main drive.

The house is surrounded by gardens (265327; 700265).

Sources:
Cadw 1998: Register of Parks and Gardens of Special Historic Interest in Wales: Conwy, Gwynedd & the Isle of Anglesey, 292-5 (ref: PGW(Gd)25(CON)).
Ordnance Survey second-edition 25-inch map: sheet Merionethshire XIV.15 (1901).
S.P.Beaman and S.Roaf, The Ice Houses of Britain, p.536.

RCAHMW, 18 June 2022