The clock tower stands above the Portico of San Giovanni on Piazza della Libertà. Built in 1527 to a design by Giovanni da Udine, it carries two bronze figures — known as i Mori — who strike the hours on a bell. They are direct copies of the figures atop the clock tower in Venice's Piazza San Marco, a deliberate reminder of which power ran the city at the time.
The bronze mechanism has been restored repeatedly over the centuries; pause in the square at the top of an hour to hear and watch them work.