A sestiere (plural sestieri) is one of the primary divisions of Venice. The city is divided into the six sestieri of Cannaregio, San Polo, Dorsoduro (including the Giudecca and Isola Sacca Fisola ), Santa Croce, San Marco (including San Giorgio Maggiore) and Castello (including San Pietro di Castello and Sant'Elena ). Each sestiere was administered by a procurator and his staff.

These districts consist of parishes - initially in seventy in 1033, but these were reduced under Napoleon and now number thirty-eight. These parishes predate the sestiere, which were created in about 1170.

Other islands of the Venetian Lagoon do not form part of any of the sestieri, having historically enjoyed a considerable degree of autonomy.

Each sestiere has its own house numbering system. Each house has a unique number in the district, from 1 to several thousand, generally numbered from one corner of the area to another, but not usually in a readily understandable manner.