The Weltermolen is an 18th century watermill located on Welterkerkstreet in the town of Heerlen-Welten. The mill was built at the start of the 18th century, and was originally used as a corn mill. The mill was originally a part of the estate of the Welten castle. The Weltermolen was restored in 1981, and officially re-opened in September 1982 by Mayor Reyen of Heerlen. The Weltermolen is open to the public on the third Sunday of each month.