The ceiling has two states and the walls have three states. If the ceiling and chandeliers start out like this state:
They will change to this:
And when the change time comes, the walls disappear completely.
Then at the next change another wall appears that has solid stone work along with a steal supporting structure that has working doors. This wall weighs about 34,000 lbs. There are no hydraulics involved. Everything moves by an electro-mechanical mechanism.
If you would like to see all this in action, just stop by the Switch some evening and be entertained by a room.