Peek a boo!

This amused me today,  I don't think I've noticed such a thing before.  
This is on the upper floor of the gallery based in the old Dean Centre /College /Orphanage - or Modern 2 as it is known now.
I don't know if it is a way around having to try and open a very heavy sealed glazing unit or what, but it did amuse me. I like the idea of a semi-circular window turning in a circle to open, or perhaps it is opening like a box lid, I couldn't quite see, but I could just imagine a head peeking around the edge of the opening.