It's the Pieta!!
He actually signed the strap that's going across her chest, after he finished it and had it on display. He signed it because people thought it was another artist's work and that royal pissed him off, so he broke into the vatican at night and signed the strap across her chest. And the original has been fixed, the madman took off her nose >.< Horrible thing to do to such a wonderful sculpture.
This is an awesome picture. I love the lighting in this.