Greenhill Farm-house is situated on an elevated site at the north-west corner bank of a former Roman fort (Pen-y-Gaer).
It is an early C19th, stone-built, slate-roofed, 2-storey building, with a central-entry-stair, end-chimney plan and rear lean-to. The south-east elevation has symmetrical fenestration of four small-pane sash-windows to first-floor with a larger pair of 3-light sashes flanking the six-panel door entrance at ground-floor. At the rear there are three window openings, a doorway and gabled dormers to the lean-to attic rooms.
The interior ground-floor has two large rooms, a parlour and kitchen/living-room to its front, each with flat stone voussoirs to fireplace and former plastered ceilings. At the rear there is a back kitchen with fireplace, site of bread-oven & boiler, and a pantry and service room.
A central staircase (removed) provided access to the first-floor main rooms each with gable-end fireplaces (internal partitions removed), and to three rooms in the rear lean-to One fireplace at the north-east has a moulded iron surround with moulded timber mantle-piece and decorated sides to its iron grate (see photo).
The 3 roof-trusses of pine are mortice & tenoned at apex having lapped & bolted tie-beams, tusk-tenon deep section purlins and a vertical ridge.

Outbuildings to the north-east consist of a pony & trap house, a pig-sty & yard and a poultry house & yard. There was a lean-to pump-house against the pony & trap house north-west side. These early C19th buildings are stone built with slate roofs, having pine roof-trusses & rafters.

Building visited during renovation and modernisation, Geoff Ward, 17/05/2000.