From "The Lives of Elevators" in the New Yorker.
In most elevators, at least in any built or installed since the early nineties, the door-close button doesn't work. It is there mainly to make you think it works. (It does work if, say, a fireman needs to take control. But you need a key, and a fire, to do that.) Once you know this, it can be illuminating to watch people compulsively press the door-close button.