Newmills is a cluster of mills on the River Swilly about 5 kilometres west of Letterkenny, off the Churchill road. The oldest building is around 400 years old; in Victorian times a flax mill supplied Ulster's linen industry, while a corn mill ground barley, oats and imported maize. The settlement grew to include a pub, a scutcher's cottage and a forge, and in the early 1900s it supplied butter, bacon and eggs to Sir Thomas Lipton's new grocery business in Glasgow.
The great waterwheel that drives the corn mill still turns and is one of the largest working waterwheels in the country. Entry is free. It is open daily in summer only (mid-May to early October in 2026), and it is on the way to Glebe House and Glenveagh.