Walkmills, 157 Drumsurn Road, Limavady, Co Londonderry, BT49 OPE

Walkmills is a storey and a half farm house of five bays, originally proportioned and detailed in a simple but elegant manner. Part of the original structure may date to the 17th century, but the surviving historic styling relates mainly to the Georgian period, with construction likely dating to 1780–1799. The house is built of local stone rubble with butter-pointed joints, rendered with dry dash, and roofed in natural slate with three dormers aligning with the central bays on the front east facade.

The front elevation features 12-pane Georgian sash windows to the remaining four ground floor bays, a central modern door with no fanlight, and three rendered chimneys on the ridge with one on each gable and a third between the central bay and the southern bay. The south gable is smooth rendered with two double-pane sashes lighting the attic. The dormers are fitted with Victorian four-pane sashes. A two-bay return projects from the second bay to the north of the gable, its eaves aligning with the main house, with a modern window and door facing south onto a garden bounded by the Castle river. The rear elevation retains one unaltered Georgian 12-pane sash on the northernmost bay; other windows are modern. The rear walls are dry dash rendered with a concreted yard on the northern side of the return, whilst rubble stone is exposed and butter-pointed facing the garden to the south.

The house is located on ground sloping from Drumsurn Road, 12 metres to the east, with a lawn between the building and the road. A former mill race bounds the site on the south side, and a concrete entrance drive on the north, with a curved gravelled area in front of the house.

The building has significant historical interest as a former cloth mill. Documentary evidence from the Ordnance Survey Memoirs records that "Cloth mill in Ballymully is supplied with water from the Castle River and works three days in the week alternately with Ardmore flax mill, which is supplied by the same mill stream. This mill has been working since Cromwell's war." Further records note that "Ballymully cloth mill is on the property of Marcus McCausland Esquire of Fruithill… can dress 200 yards per week. Under the roof of the dwelling house, can dye black, brown, green, red, yellow and drab." This evidence indicates the house was originally part of the cloth mill complex. The 1830 Ordnance Survey map shows the present building, though it appears to have extended at least two bays further to the south; a smaller building, now ruined, sits to the east. By the 1858 Griffiths Valuation, the owner was still McCausland, with Thomas Gault (formerly tenant of the flax mill) now occupying these buildings, valued at £9.0s 0d, designated as a 'tuck' mill. The flax mill was valued at £8.10s 0d. On the 1904–6 Ordnance Map, a gap appeared between the present building and a southern extension now indicated as a corn mill, with ownership having passed to John Loughery, grandfather of the present owner. The corn mill ceased production in the 1920s and was subsequently demolished. The flax mill remained in production until 1947 when it was badly destroyed by fire.

Later alterations include the addition of three dormers to servants' rooms in the attic during the late Victorian period. The stone facade was rendered over during the 1930s. The hall was originally divided by a timber screen behind the stair, which was removed in the 1970s.

The site is of particular archaeological interest for its complicated mill race arrangements designed to ensure sufficient head of water to serve two working mills, and the scant remains of the former flax mill survive to the south, alongside more recent farm buildings. Walls and foundations of the former cloth mill survive adjoining the house to the north and to the east.