This is such a fantastic piece of IA (installation art) from Maurizio Cattelan.
I found it at another blog. Will try to rediscover the link.
It says the lifts behave like real (sounds and actions, even the number lights work). Cool, isn't it? One of those IWIHTOT ("I wish I had thot of that") moments. But the clever bit is that when you place something inside one of the cars, it disappears and re-appears at the other side.