As a matter of fact, squares in Venice are not called “piazza” (Italian for squares). Except for two of them (Piazzale Roma and Piazza San Marco), they are called “campi” which literary means “fields” since they used to be meadows vegetable gardens.
Small squares are called “campielli”. In the middle of many campi and campielli you find wells. Most squares are called after the churches or palaces standing next to them, famous people or professions.
Among the squares I like to use during my photo sessions in Venice you find Campo Santa Margherita, one of the widest ones with plenty of typical Venetian bars and cafés and some trees offering shadow; Campo San Giovanni e Paolo hosting the homonymous Church and the Captain-General Bartolomeo Colleoni’s statue; Campo della Salute in front of the Salute Church, covered with white marble slabs and offering a a gorgeous view on the San Marco Square.