Penllwyn, former manor house now Penllwyn Arms public house

The building, now the Penllwyn Arms public house, was originally a manor house, likely dating from the 18th century. It is a long, rectangular structure built of rubble with ashlar dressings and a stone tile roof. Prominent features include a large ridge stack over the porch bay, a pair of angled stacks at the right end, and additional stacks to the rear. The house has two storeys and an attic.

The five bays are arranged around a central, two-storey porch with a hipped roof. Windows have diamond mullions set in ashlar surrounds, with metal-framed casements and quarry glazing; remnants of the original leaded lights remain. The left wing features windows with hoodmoulds, while those on the right have relieving arches over them. The central porch has a two-light window on the first floor, and the main entrance below has a four-centred arch with rough voussoirs and a surround. The entrance features a boarded door with a grille and decorative hinges, and a three-light side window. The stonework at the base of the walls is battered and rests on boulder footings.

To the left, each bay has a narrow, steeply-pitched gable with sprocketed eaves, a single rectangular window in the attic, a four-light window on the first floor, and five on the ground floor. The bays to the right are similar but wider, with two-light windows to the attic, paired double-light windows to the first floor, and three-light windows at ground level. Doorways are located to the left side of each bay on the right, with the right-hand doorways now the main entrance to the public house, set under a relieving arch (with a blocked window to the right formerly present). Segmental arches are found on the left side. Some openings show evidence of alterations.

The downhill-facing gable end is a rebuild or extension, featuring the twin stacks set astride the gable and uniform small mullioned windows under relieving arches (two to each floor). A large external stack is also present. A flat-roofed extension to the rear obscures the main building, but changes in roof pitch reveal a division between the two wings and the irregular E-shaped plan of the north wing. This north wing comprises three steeply gabled wings of varying depths, with a stepped stack in the wing to the left, a rendered facade with an attic light in the centre, and a slightly lower wing to the right with a narrower bay stepped down to the rear. Viewed from the side, a single half dormer with windows similar to the front is present, along with an additional pitched roof extending over an outshut from the rear bay. A short section of wall extending from the front left incorporates an archway.

The interior has been largely remodelled over time, with fireplaces blocked. The ground floor comprises two large rooms, each extending across two bays. A replaced staircase rises to a large first-floor room with a chamber over the porch. The original roof structure consists of pegged A-frame trusses, bearing carpenters' marks, which are partially visible in the first-floor rooms.