Slighly downstream from the powerhouse is this ruined mill built into precipitous side rocks of the River Roe. Rubble stone in its lower storey and brick to first floor it appears fairly typical of the ruined mills in the modern country park. However, there have been suggestions that this structure may be on the location of, or may partly date from, the Anglo Norman occupation of the area in the Twelfth Century. Two mills of the ‘Roo' were recorded in an inquisition of 1333 at the time of the death of Richard de Burgo The Red Earl of Ulster. The building is marked on the first Ordnance Survey Map of the area of 1831. By 1848 it is labelled ‘Old beetling mill’ and indicated as roofless by 1907. It is likely that it was used for a number of functions during its history, as a corn mill, and as a beetling mill associated with the Linen Industry. Today it is located in a quiet corner of the park and is a great dramatic ruin
