Melin Gwalchmai Gwalchmai · Isle of Anglesey · Wales

Melin Gwalchmai stands south-west of Gwalchmai on land formerly belonging to the Treveilyr Estate. It is a full-height three-storey tower windmill, circular in plan, with slightly tapering rubble-masonry walls that were once rendered. The mill forms part of Anglesey's distinctive wind-powered corn-milling landscape, where exposed conditions and extensive grain production supported many tower mills in the eighteenth and nineteenth centuries.

The mill was probably built in the early nineteenth century. In 1841 the land on which the windmill stood, together with the nearby watermill near St Morhaiarn's Church, was occupied by William Williams. After his death later that year, the properties were taken over by his son, also William Williams. During the following decades the windmill was worked with the assistance of Lazarus Roberts and other millers and labourers. By 1861 William Williams had employed Robert Williams, son of a coal miner from the Gaerwen area, as a servant. Robert Williams learned the milling trade and continued running the windmill until his death in 1919. His nephew Thomas Williams, who had been his assistant before 1901, then took over the business.

Melin Gwalchmai continued to work by wind power until 1927. The sails and cap were then removed and the top of the tower was sealed with a concrete roof. The mill did not immediately cease working: a diesel engine was installed in a corrugated-iron shed next to the tower, and a drive shaft ran from the engine shed through a cellar beneath the mill to the millstones. This allowed milling to continue for several further years.

The tower survives in good condition. The machinery has been removed, but some wooden beams and one of the millstones remain inside. The exterior retains ground-floor doorways with segmental heads of rough voussoirs and rectangular windows at the upper stages. Melin Gwalchmai was listed at Grade II in 1971 as one of Anglesey's substantially intact surviving windmill towers.