Legend has it that one day Queen Christina of Sweden was in Castel Sant'Angelo and had an appointment with a painter at Villa dei Medici. She was late and decided to let him know she was arriving and "knock" on the door. How? Shooting a cannonball. Despite the distance, 1.4km, and the uncertainty, 3 cannonballs were shot and one reached the target. Today, you can see a circular mark on the main gate of Villa dei Medici, while the cannonball is inside the fountain just in front of the entrance.