Byrne's installation is a lone organ sitting in the midst of a huge room, with wires running from the organ to every corner of the room. As you play keys on the organ, hammers hit pillars, air rushes through pipes, and motors vibrate the structure, and you are literally "playing the building."
I didn't actually play, since the line was long and it was more fun to wander around the room and be surrounded by the noises. Even on a sunny Friday afternoon, it's thoroughly spooky, especially since you enter and leave through the deserted entrance hall to one of the ferry slps.
It's a fascinating installation in a wonderful old building and I think I'll be going back.