The Pic du Midi Observatory lies on top of a 9,439 feet mountian in the French Pyrenees. Its construction started in 1878, and in the 1960s was used by NASA to take detailed photographs of the surface of the Moon in preparation for the Apollo missions.
It is the home of many different telescopes, one of them open to amateur astronomers.
And, oh, there’s a restaurant in it.
Official website in french here.
Submitted by Vitor Diel/bumerangue.