This is a skull at des Catacombes, a truly amazing museum (?) in Paris. It's a whole series (several km.) of underground tunnels below the city, all lined with thousands, maybe millions, of human bones. The bones were relocated from cemeteries that were removed in the 1800s I think. It's artistic in a way, because in lots of places the bones are stacked so as to make various designs on the walls. But mostly it's just weird. Somebody (many people) must have really had too much time on their hands...