As you enter the magnificent Piazza San Marco, it's one of the first things you see, standing on the north side, the centerpiece of the stately white Procuratie Vecchie (the ancient administration buildings for the Republic). The Renaissance clock tower, with its distinctive blue face ringed by astrological symbols, was built between 1496 and 1506, and the clock mechanism still keeps perfect time. On the top, two bronze figures, known as “Moors” because of the dark color of the bronze, pivot to strike the hour. Visits inside are by guided tour only (included in the price of admission), but unless you are interested in the clock’s history, these are easily skipped, especially if you’ve already been up the Campanile di San Marco.