Riverside Mills, Dunsdale Road, Dunsdale Haugh, Selkirk

Riverside Mills comprises a complex of buildings dating from 1837, expanded in the mid-19th century, situated on the edge of Selkirk. The site originally housed a spinning mill, followed by a new mill constructed between 1863 and 1865, along with associated workshops and stores. The buildings are primarily constructed of whinstone rubble with sandstone dressings and slate roofs.

The original spinning mill, dating to 1837, is a three-storey and attic, 17-bay structure with a nine-bay rear wing containing the former wheelhouse. A gabled stair tower is located at the north-east re-entrant angle. A single-storey, two-bay, M-roofed milling house, later used as a joiners/maintenance workshop, was added to the rear between 1863 and 1865, featuring a four-pane window. Inside, the original mill retains timber cross beams supporting mule headstocks and a collar-beam roof, with some skylights covered by slate. The ground floor of the rear wing originally contained wheels, which were replaced by twin Leffel turbines in 1871 (not visible in 1996).

The new mill, built between 1863 and 1865, is a three-storey, four-by-16 bay structure. Eight bays were constructed in 1863, with a further eight bays added in 1865 on either side of an advanced gabled stair tower featuring a large fanlight oculus. The southwest gable bears the inscription "WT 1865," and slits are visible in the north gable. A pitched roof, hidden behind gable parapets, incorporates drainage channels. The interior consists of timber beams resting on three rows of spigoted cast-iron columns, along with a timber newel stair.

A small single-storey and attic batching oil store has been altered to serve as a canteen, with modern windows.

The former engine, willey, and boiler house, now an engine shop, is an L-shaped building. It incorporates a beam engine house with a tall, round-headed window, a dentil course, and a cast-iron roof tank. A two-storey and attic, two-by-five bay boiler house adjoins it, featuring ground floor arches partly concealed by a later lean-to. A single-storey, piend-roofed willey house sits over the lade. The interior of the engine house contains a cast-iron framed and stone flagged platform on the original beam engine entablature, with provision for a 22-foot beam, parallel motion brackets, decorative stair and railings, and ceiling hooks. A perforated iron floor serves a drying room above the boiler house.

A small, four-bay power loom weaving shed, later used as a wool store, is accompanied by a two-storey, five-bay rear extension. The elevation facing the street is harled, with piended roofs. Simple single-storey offices are located to the northeast, with an early 20th-century gabled extension and an enlarged window.

Finally, the R and D Workshop and Offices are likely the remains of former hand-loom shops, consisting of a two-storey, 12-bay structure with a six-bay addition in a similar style. Ground floor windows are blocked, and iron tie-plates are visible. A stack is present on the harled gable, marking the site of a demolished lodge. A modern first-floor line indicates the presence of a former dyehouse.