Castle Mill Wheelhouse Block on River Edge

Castle Mill is a mill building located on the river edge, dating from the late 18th century and built for John Lomas. The structure features a ground floor made of coursed squared gritstone, with red brick above, and is topped with a Westmorland slate roof. It stands three storeys tall over the wheel race and has a layout of seven bays by three bays.

The north facade showcases boarded small-pane sash windows on the ground floor, which are set in flush wood architraves with stone lintels and projecting stone sills. The first and second floors are adorned with 25-pane unequally-hung sashes that sit under cambered brick arches, with a blocked central opening on the second floor. Stone bands are present at both the first and second-floor levels, and similar windows can be found in other parts of the building. The roof is hipped and lacks chimneys.

Inside, the mill race and turbine machinery remain, though they are in poor condition. The ground and upper floors still contain original timber work, along with pulleys and straps that were part of the power system, but the interior is in a dangerous condition. Attached to the south-west end are brick outbuildings, including the engine house and stack, which were built when a steam engine was installed in 1847. A water wheel was first erected on this site in 1764 to pump water up the gorge into the town, and a new water wheel was constructed in 1790-91 for John and Charles Lomas when plans were made to build a cotton mill on the site.