Trewyn Manor (nprn 20926) is located above the west bank of the Afon Honddu, to the north of Abergavenny, just to the east of the Black Mountains. Located in a small landscape park (700241), the house is flanked by a garden on its east and south sides where the sloping ground has been terraced. 

To the east (the main front) is a rectangular garden, virtually unaltered since it was made in the late seventeenth century, enclosed by a high stone and brick wall on all but the east side which is closed by railings and central gates. Next to the house are two stone-revetted terraces linked by central stone steps in three flights, with views from the top terrace down what remains of the Scots Pine avenue (a rare survival).

Along the south side of the house is an upper narrow terrace, part of the original seventeenth-century layout. Below is a wide rectangular terrace built up over the slope with stone retaining wall. This is now grassed over, but a gravel perimeter path can be made out beneath the turf. Below, a stone and brick wall encloses a narrower, sloping rectangular area, formerly an orchard and kitchen garden but now rough grass. These lower terraces are of nineteenth-century date replacing the former seventeenth-century layout on this side. On the western edge of the garden below the house are several narrow, linear ponds fed by a stream, dammed and with sluices, though now silted-up. To the east of the ponds, on ground sloping steeply to the east, is an area of ornamental woodland (coniferous and deciduous), mostly planted in the early twentieth century.

Sources:
Cadw 1994: Register of Parks and Gardens of Special Historic Interest in Wales: Gwent, 152-3 (ref: PGW (Gt)(MON)).
Ordnance Survey first-edition 25-inch map: sheet Monmouthshire XXX.2 (1879); first edition six-inch map: sheet Monmouthshire XXX (1880).
RCAHMW air photos: 94-CS 0558; 945074/44.

RCAHMW, 13 June 2022