Gyrn Castle, a nineteenth-century house incorporating features from both the late seventeenth century and eighteenth century (35857), is located in a wooded valley to the east of Llanasa. It lies in a landscape largely fashioned in the nineteenth and early twentieth centuries. The grounds are roughly rectangular on plan, extending between the villages of Llanasa and Glan-yr-afon, bounded by public roads on the east and west, and elsewhere by farmland. In their present form they are probably, mostly, contemporary with the major remodelling of the house, 1817-24.

The present main (west) drive, flanked by deciduous trees, runs from Llanasa eastwards to the house, the entrance flanked by a single-storey lodge. The disused east drive, from the village of Glan-yr-Afon, has a similar lodge at the entrance (35858). A short branch drive with an informal avenue of mixed deciduous trees runs from the north, off the Llanasa to Glan-yr-afon road, to the house. This entrance is marked by a castellated arch gateway, iron gates and octagonal lodge (35859).
Although lacking a park as such, the field south of the west drive is dotted with trees and a clump, giving it a park-like character.

In front of the house, to its north-east, is a large area of lawn affording views to the Hillbre Islands and the Wirral. On a steep slope below the house is an enclosed area of nine terraces, narrow and broad, dry-stone revetted, and reached by steps down either side. Nearby planting includes monkey puzzles and Scots pines.
In woodland to the south-east of the house a series of five lakes in the valley forms the focus of the pleasure garden, made by widening the Afon-y-garth stream. The central lake is the largest, with two small islands. Around it lie an ice house (405463), a ruined boathouse and an artificial otter holt. The other lakes are much smaller. All are surrounded by wooded banks, planted mostly with beech and horse chestnut with an underplanting of rhododendrons. A summerhouse once stood on the south-western corner of the wood. An earthen path makes a circuit walk around the woods and lakes. To the north of the ponds is a rock garden accessed by rustic stone steps; artificial waterfalls run into a small moat around its base.
A small kitchen garden with castellated walls is built into the boundary wall of the farmyard, to the west of the house. Some old fruit trees on the walls survive.

Sources:
Cadw 1995: Register of Parks and Gardens of Special Historic Interest in Wales, Clwyd, 112-4 (ref: PGW(C)33).
Ordnance Survey, six-inch map: Flintshire II (first edition 1871).

RCAHMW, 14 June 2022