Castle-upon-Alun House including attached stone walls enclosing garden, and outbuilding

Long 2-storey range with rear wing. Entrances in the angle of the main range and rear wing. Long garden front faces S. Rough cast over masonry under steeply pitched slate roofs. Two masonry end stacks and 2 masonry ridge stacks to main range; 3 masonry stacks to rear range. Fenestration is generally 12-pane horned sash windows with flat heads and stone sills.

The main range consists of a lower 2-window unit towards the centre, flanked by a symmetrical 3-window addition to the L and a 4-window addition to the R with 2 gablets. The central unit has 2 narrow sashes to the upper story offset to the L. The lower storey has a C20 half-lit door to the R and a 4-light C20 window to the L. The L addition has 3 sash windows to the upper storey and a central half-lit door with overlight to the lower storey flanked by sashes. The R addition has 2 gablets with wide barge boards. Each gablet contains 2 half-dormer sash windows. There are 3 windows below, symmetrically placed.

The rear wing is offset to the W. The W gable end of the main range has no openings. The W side of the rear wing has 5 windows to the upper storey and 3 to the lower storey. There are 2 gabled attic dormers with multi-pane windows. The N gable end of the wing has wide barge boards. The ground floor has 2 sash windows and a small C20 window to the L.

GARDEN WALLS: Attached rubble walls define the garden to S and E of the house. The Gothic doorway near the SW angle of the house probably reuses medieval stonework; similar Gothic doorway at SE angle of garden walls. A square stone outbuilding is incorporated on the E side.

Entrance hall with large stone fireplace on the S side with a moulded Tudor arch. Straight staircase on W side of hall;beamed and pargetted ceiling. The reception rooms are to the S of the hall, with the main room at the end. The central reception room has a boarded door leading to a fireplace staircase to the L of the (now Victorian) fireplace. The doorway is at a 45° angle to the wall. To the R of the fireplace is a small lobby, perhaps reflecting the original end entry to the house. It now leads to a door to the garden. Internal detail of the house includes wainscot panelling, decorated and moulded coving and plastered ceiling beams.