the Piazza San Marco and Piazzetta contain the Venetian basilica, the 500-year old Clock Tower and the Doges' Palace. 
Venice's dazzling basilica, the Doges' Palace (Palazzo Ducale), and the 500-year-old Clock Tower (Torre dell'Orologio), all within the sprawling Piazza San Marco and adjacent Piazzetta, are the very focus of the city's life.