Downhill Palace, Mussenden Road, Downhill, Castlerock, Co. Londonderry, BT51 4RP

Downhill Palace is a detached, symmetrical, multi-bay two-storey stone building over a raised basement, built between 1775 and 1785 as a Bishop's Palace for the Earl Bishop Frederick Augustus Hervey to designs by Michael Shanahan. The building was gutted by fire around 1851 and subsequently rebuilt around 1876 to designs by John Lanyon. It is now Grade B1 listed.

The palace is U-shaped in plan, facing south with an enclosed yard to the rear and a further pair of bow-ended yards to the north. The building was sold in 1918 and subsequently partially dismantled, though the external elevations remain. The National Trust consolidated the structure around 1960, and the building now forms part of Downhill Demesne, run as a public park.

The roof and partial dismantling of the east and west rear wings occurred between 1920 and 1980, with the principal south front elevation remaining largely intact. The symmetrical front elevation is nine windows wide, featuring a pair of full-height three-sided canted bays at either end and a central doorcase accessed via a double perron. The basement level is constructed in rusticated sandstone ashlar, while the ground and first floors are built of coursed smooth sandstone ashlar. Each window is flanked by fluted Giant Corinthian pilasters rising from a continuous ground floor sill course and supporting a fluted cornice with wave-moulded frieze. Window openings are square-headed, formed in voussoired sandstone with cut sandstone sills; the windows themselves have been removed. Basement-level windows have segmental heads, now rendered over.

The central entrance bay is square-headed and flanked by Corinthian pilasters with an architrave surround on plinth blocks, fluted frieze, and cornice supported by scrolled console brackets with bell-flower pendants. The door has been removed, and the opening now leads onto a paved platform with two flights of swept steps fitted with replacement iron railing. The perron is constructed in vermiculated sandstone blocks, though only partially extant, with cement render applied to the remainder.

The west side elevation to the principal block is nine windows wide, extending northwards by a further five windows to what was formerly a two-storey wing with two full-height bows extending further north. This rear wing is now largely dismantled. The west elevation is detailed as per the front elevation, except that first-floor windows to the bow have segmental-headed openings. The northernmost bow retains a round-headed door opening flanked by Ionic columns and responding pilasters, now rendered over. The west elevation to the upper yard projects beyond the west wing by a single bay with a shallow arcaded elevation built in rubblestone with some segmental-headed window openings.

The northwest bow-ended yard is enclosed by a tall rubblestone wall with crenellated parapet, featuring a single round-headed blind carriage arch opening now infilled. A short crenellated rubblestone screen wall projects westwards and terminates in a tall square pier.

The north elevation to the lower yards comprises two crenellated bowed walls with a central round-headed carriage arch opening formed in rock-faced basalt ashlar with a crenellated parapet wall and wrought-iron gates.

The east elevation mirrors the west elevation, except that the upper yard has multi-bay two-storey rubblestone walling with segmental-headed window openings formed in voussoired stone with stone sills, largely rendered over at ground floor level.

The principal south block has cement-rendered walls to the inner elevations and is set out in lawns and gravel footpaths. The former rear elevation has largely disappeared except for a two-storey central bow, formerly containing the staircase, which retains coursed smooth sandstone ashlar walls surmounted by a wave-moulded frieze and voussoired window heads. The west wing has a bowed end to the upper yard with a central square-headed door opening detailed as per the principal front entrance. The east wing has partially intact sandstone ashlar walling with a Venetian window opening, now rendered over, and a bowed end facing the upper yard.

The north carriage arch opens into a central passageway enclosed by crenellated rubblestone walls to the northeast and northwest yards, each having a single round-headed carriage arch opening built in voussoired squared basalt with impost blocks and replacement iron gates. The passageway is aligned to provide views of Mussenden Temple from the rear of the house. Both yards are currently being excavated and partially reconstructed. At the south end of the passageway is a pair of round-headed arches with oculi over each, opening into the upper yard.

The south elevation to the upper yard is cement-rendered with a central pedimented breakfront housing the carriage arch, built in block-and-start vermiculated sandstone with stepped vermiculated keystone. The lateral walls are arcaded, joined by sandstone impost stones and featuring lunette openings to ground and first floors.

The building is located on an elevated site to the south of the north County Londonderry coastline and to the east of Mussenden Road, set in expansive meadows forming part of Downhill Demesne public park. A rubblestone ha-ha runs in front of the south elevation. The setting includes a Mausoleum to the south, Mussenden Temple to the north, an orchard and dovecote/ice-house to the west, and the principal entrance to the southwest.