Of the 14 windmills (moulins) that used to sit atop this hill, only two remain. They're known collectively as Moulin de la Galette—the name being taken from the bread that the owners used to produce. The more storied of the two is Le Blute-fin. In the late 1800s there was a dance hall on the site, famously captured by Renoir (you can see the painting in the Musée d'Orsay). A facelift restored the windmill to its 19th-century glory; however, it is on private land and can't be visited. Down the street is the other moulin, Le Radet.
Le Blute-fin, corner of Rue Lepic and Rue Tholozé, Paris, 75018, France