The Hartwerd Windmill is a relatively modern windmill located on the Oldeclooster in the town of Hartwerd. The mill was built in 1925 to a relatively rare American design, and is now a listed building. The Hartwerd Mill is owned by the Wunseradiel Mill Foundation, and serves the Old Vaard Monastery. The mill is not currently open to the public, as it is undergoing extensive restoration work.