This is really going off at a tangent, but I'll say it anyway.
Apologies if someone has mentioned any of these before, my fault for coming late to the thread.
Everyone seems to agree that the presence of a door either side of the central feature at the end of the room is unusual. It made me think of a court room or throne room, with an ante chamber behind it.
And on the left hand side, on the wall beyond the "puppet" in a glass case, might that be some sort of curtain covering something?
The vaulted ceiling is very low, so it could either be cellar like or under the main floor of the room, or it could be right at the top, like in a Scottish tower castle. The dividing ribs are however quite thin so I'd be inclined to err on the side of a building on the upper floors, with only the roof above it.
All the contents seem to be put there deliberately to confuse - they sure have succeeded!

Nell