Melin-y-Borth was built in 1816 in a commanding position overlooking Amlwch harbour and at 18m it was the tallest windmill on Anglesey. Its tower is comprised of two-storey cellars below ground level and a ground storey built of rubblestone, all surmounted by a brick-built tapered tower housing three further storeys and the cap floor. A complex of buildings surrounded the tower on all but the south-east side, and the tower had a wide wooden gallery at second floor level (the base of the brickwork), supported on wooden props and on the roof of one outbuilding. Inside were four pairs of stones, for wheat, barley, oats and maize, and it was reputedly able to grind 70 bushels of corn in an hour.

The mill ceased work in the early 20th century, and the machinery was removed and the outbuildings demolished. In 1975 the cap frame remained in situ at the top of the tower.

Since the closure of the nearby oil terminal the tower has been stabilised, with the rubblestone section repointed and accessible entrances blocked. Two of the major cross timbers are still in position, marking the former position of the great spur wheel, and the cap frame appears to have been replaced with new timbers.
W J Crompton, RCAHMW, 24 September 2008.