"Oubliette" in French literally means "forgotten room", a form of dungeon which was accessible only from a hatch in a high ceiling.
Also it's the title of an X-Files episode :)
The room itself here is not my image, it was kindly lent to me by one of my contacts, Trueth. Brian has an absolutely amazing set taken in an abandoned prison, which you can see here. He very kindly sent me several images from this set, because I wanted to make a Rapunzel picture to carry on my fairytales, and I thought these fit in very well with a dark theme. Whilst this one isn't Rapunzel, it's an outtake which I quite liked. I'm still working on a Rapunzel, especially as I forced my friend Lisa to pose in a wig for it...