The Oil Mill in Heerlen is a beautiful windmill with a very long history. The oldest parts of the mill date back to 1502. Over the years, the mill has been altered several times. In the 19th century, the mill was converted into a corn mill. Today, the mill is privately owned, and is used for commercial purposes. The mill is open to the public during business hours on Tuesday to Saturday each week. There is a small shop in the mill which sells flour and other baking products.