San Marco basin in the context of Riva degli Schiavoni

Piazza San Marco (Italian pronunciation: [ˈpjattsa sam ˈmarko]; Venetian: Piasa San Marco), often known in English as St Mark's Square, is the principal public square of Venice, Italy, where it is generally known just as la Piazza ("the Square"). The Piazzetta ("little Piazza/Square") is an extension of the Piazza towards San Marco basin in its southeast corner (see plan). The two spaces together form the social, religious and political centre of Venice and are referred to together. This article relates to both of them.

A remark usually attributed (though without proof) to Napoleon calls the Piazza San Marco "the drawing room of Europe".