I already know the ending. Known it for months.
Gordon and Batman stand on a rooftop, some days after Gotham has been saved. Batman is about to jump off the ledge and fly away when he turns to Gordon and says:
"Why do we fall commissioner?"
Gordon shakes his head
Batman says:
"So we can learn to pick ourselves back up"
Then he jumps off and glides away,
then the camera switches to a first person perspective and you see a huge question mark on one of the skyscrapers, with "Riddle me this" written under it. Hanz Zimmer takes it from there as the credits roll.