On Easter Sunday Florentines and foreigners alike flock to the Piazza del Duomo to watch as the Scoppio del Carro, a monstrosity of a carriage, pulled by two huge oxen decorated for the occasion, makes its way through the city center and ends up in the piazza. Through an elaborate wiring system, an object representing a "dove" is sent from inside the cathedral to the Baptistery across the way. The dove sets off an explosion of fireworks that come streaming from the carriage.
You have to see it to believe it. If you don't like crowds, don't worry: video replays figure prominently on the nightly newscasts afterward.