The grounds of Tan-yr-allt villa (nprn 16896) were laid out soon after the house was built by William Madocks in about 1800. The house is perched on a steep hillside looking south over Porthmadog and Traeth Mawr, with a view down to Harlech and beyond, and a sheer rock face as high as the house immediately behind it. The grounds extend along, mostly, the north side of the A498, the villa located at the west end. There is only a small area of parkland to the south of the house, at the foot of the slope, but a large expanse of semi-natural woodland on the steep, craggy slope to the north and east of the house is part of the designed landscape.

The woods above the house were present when Madocks acquired the site, and consist mostly of sessile oak. Madocks added other trees, especially beech, many plantings of which survive and are one of the best features of park and garden. The woods retain their semi-natural character, and the trees within them regenerate naturally. The field south of the house, between it and the road, an area of former parkland, slopes to the south, and has scattered immature trees; part has been planted with fruit trees.
The elevated site required long drives, climbing from east and west, off the main road. The east drive retains many good trees, and has a lodge (16899), also designed by Madocks, at the entrance. Just to the east of the house it crosses a stream, the naturally steep course of which has been altered by the addition of pools and waterfalls, creating both sights and sounds to be appreciated from the drive.
The presumed Roman altar (309647), south-east of the lodge, in the small part of the grounds south of the road, is likely to have become an ornamental feature, providing a focus for walks & rational conversation.

Gardens lie around and to the immediate east of the house (301636).

Source:
Cadw 1998: Register of Parks and Gardens of Special Historic Interest in Wales: Conwy, Gwynedd & the Isle of Anglesey, 296-99 (ref: PGW(Gd)18(GWY).
Ordnance Survey second-edition 25-inch map: Caernarvonshire XXXIV.12 (1899).

RCAHMW, 22 June 2022