The clock tower was built by the architect Mauro Coducci in 1496-1499, the side additions were made in 1500-1506 to the design of Pietro Lombardi, and the superstructures were made around 1755 by Giorgio Massari.
The tower is topped by a flat roof on which an architectural group is installed: two bronze figures, so-called "Moors" because of the tarnished bronze, striking the bell with their hammers have been beating the time hourly for four and a half centuries. "Moors" were cast in bronze by Amoroggio della Ancore in 1497.
Beneath the crowning element of the tower is the coat of arms of Venice, a winged lion. Below the coat of arms is a semicircular ledge with a niche and two side doors. In the niche is a Madonna and Child made of gilded copper. On the day of the celebration of the Ascension and throughout the solemn week, the side doors, at every strike of the clock, open and out of them, following the angel, come the Magi, who pass in front of the Virgin Mary, bowing to her.
Under the ledge, in the 15th century, a clock with a complex mechanism was installed by Gianpaolo and Giancarlo Ranieri, father and son from Padua. The clock indicates the change of seasons, the passage of the sun in the signs of the zodiac, and the time and phases of the moon.
