The Torre dell'Orologio (Clock Tower) on St Mark's Square (Piazza San Marco) is of symbolic and historic importance in the history of Venice. The clock also known as ‘St Mark's Clock Tower’ or the ‘Moors' Clock Tower’ displays the time of day, the dominant sign of Zodiac and the current phase of the moon. This complex timepiece played a central role in the city and for centuries was the place to meet. Venetian seafarers relied on it know the most favorable time to set to sea. In 1858 the clock was made the official timekeeper of Venice and every other clock set itself to it.

In the early 1490s, the Venetian Senate decided that the told clock of Sant'Alipio needed to be replaced. Doge Agostino Barbarigo commissioned the father-and-son team of Giampaolo and Giancarlo Rainieri, engineers from Reggio, Emilia to make the new clock in 1493. It was to be most excellent clock.' Houses were razed and in February 1499 a diarist noted that ‘The clock on the square was unveiled for the first time - above the street that leads into the Merceria (a market or place of commerce). It is most beautiful and ingenious.’ The building was possibly designed by Mauro Codussi  was completed February 1, 1499.

Giampaolo and Giancarlo Rainieri became the clocks custodians. They began a five century tradition of the clock keepers and their families living in the tower. The truth is contrary to the legend that the Senate had the clock’s creators blinded on completing the clock, jealous that they would go on to repeat the marvel elsewhere. Houses were razed and in February 1499 a diarist notes that ‘The clock on the square was unveiled for the first time - above the street that leads into the Merceria [a market or place of commerce]. It is most beautiful and ingenious.’ The tower rises, through a series of rectangular storeys, incorporating the clock face and then to a terrace.