The door of St. Nicolas forms one of the ancient entry points to Florence, when the city was protected from attacks by an imposing outer wall. As little remains of the city's historic walls today, these doors, standing alone, are referred to as towers. Torre San Nicolò's name comes from the zone of Florence by the same name, where the tower is positioned. A distinguishing feature of the San Nicolò tower is that it is the only one not to have been lowered in height during the 1500s. Because of this it's the only door in Florence that can give you a real sense of what it must have been like to arrive at the gates of the city, as a visitor in medieval times.