A few weeks ago, I needed to move to a new studio.
The ceiling of the previous one had collapsed suddenly! 
I dread to think what could have been the consequences, as the sofa was under a huge slab of plaster and the floor was littered with lesser slabs.
So glad no one was there at the time.
Amazingly, none of my artwork was damaged either.
I think the ceiling must have come down in one big 'flumph' and puffed most of the artwork of the wall, so that it all landed, face down, on top of the pile of rubble. Quite extraordinary!
All they needed was dusting off.