Among Frederick the Great's Potsdam palaces sits the historic windmill of Sanssouci. Since the first mill was constructed on the site in 1738, there have been three in its place (the current one being a reconstruction after its destruction in WWII).
The first mill on this site was built on a rotating platform so that it could be moved to catch the wind. Today you can visit the interior of the windmill, where a contemporary art gallery and a small history of windmills can be found. Climbing to the top, you can also catch a good view of Sanssouci Park.