Pentre Ffynnon Mill

Pentre Ffynnon Mill is a large, 4-bay mill of two storeys and an attic, dating from the 18th and 19th centuries. It is constructed of rubble sandstone with large quoins under a shallow hipped slate-covered roof. A two-storey, open-fronted porch extends to the north and is covered by a corrugated roof. It contains three wagon bays divided by rectangular stone piers; the sides are also open, and a single-storey, U-shaped range adjoins to the east, having been altered. Wood planked bins are located in the upper storey of the porch and are accessed from the first floor. Above the porch are four square ventilation openings with wooden slats, leading to the attic.

Inside the porch, doorways lead to the left and right. The doorway to the left has a flat, chamfered stone head pierced with holes, likely reused from elsewhere, while the doorway to the right is wide, with a Tudor-arched brick head and the inscription 'I W 1823.' To the left of this doorway is a two-light window opening, which may have been inserted into a doorway, and further left is a blocked doorway with a flat stone lintel.

On the south side, a large opening, probably originally a wagon bay, has been blocked in stone and is set under a segmental head of stone voussoirs. Above this, at first-floor level, are three two-light iron-framed windows, most of the glazing now missing, set in chamfered stone surrounds with flat heads. Four square ventilation openings with retained wooden slats are present in the attic. On the lower storey are two iron-framed windows on the right, aligned with those above, with the left one blocked with stone and brick. A small square opening, now altered with a stone and brick lintel, lights the machinery. At ground level, a wide segmental arched opening fronts a wheel pit, now covered with a steel grille, which receives water from a headrace running from the south. A portion of the cast iron and wooden water wheel remains in situ; it was likely a high breast-shot wheel positioned at a right angle to the building's south wall. A wallower and wooden main shaft are also present and appear to be well-preserved.

The west end of the mill has two square ventilation openings with wooden slats to the attic and a loading door offset to the right, opening onto the first floor, with stable doors under a segmental head of stone voussoirs. Similar ventilation openings are on the east end, and a single-storey range adjoins below.

The ground floor has flagstone floors, with wooden floors above and trapdoors to access them. The right-hand ground floor bay contains wooden hoppers with attached chutes to the ceiling, along with belt drives. Wooden boarding surrounds the wheel and machinery in the centre of the south side, revealing a drive shaft with wooden pulley wheels for belt drives. A straight timber staircase is against the north wall, and the left-hand bay is open with doorways leading to the adjoining single-storey range. On the first floor, two bed stones remain in situ, between which is an iron shaft with a crown wheel, driving shafts for pulleys and wooden wheels for belt drives. The roof structure features closely-spaced timber trusses in the attic.