Piazza San Marco, often known in English as St Mark's Square, is the principal square of Venice, Italy.

A remark often attributed to Napoleon (but perhaps more correctly to Alfred de Musset) calls the Piazza San Marco "the drawing room of Europe." It is the only great urban space in a European city where human voices prevail over the sounds of motorized traffic, which is confined to Venice's waterways. It is the only urban space called a piazza in Venice; the others, regardless of size, are called campi.

As the central landmark and gathering place for Venice, Piazza San Marco is extremely popular with tourists, photographers, and pigeons.