Ca' Giustinian, Gothic palace in San Marco, Venice, Italy

Ca' Giustinian is a Gothic palace on the Grand Canal in the San Marco sestiere, formed by joining the larger Giustinian building to the east with the smaller Badoer-Tiepolo house to the west, the gap between them filled in the late 15th century. Its brick facade rises four storeys divided by string courses, with white stone-framed single lancet windows; the central bay has a round-arched portal flanked by two tympanum-topped windows, and three tiers of four-light windows with projecting balustrades above. A dentilled cornice and a long balustrade close the top terrace, and a serliana opens at ground level of the left-hand building.

Ca' Giustinian was built in the second half of the 15th century for the Giustinian family, on the site of an earlier house where Lorenzo Giustinian, first Patriarch of Venice, had lived. In the 17th century it passed to the Morosini; in 1820 it became the Albergo all'Europa. On 19 October 1866 General Edmond Le Bœuf signed there the formal cession of the Veneto to France's emperor Napoleon III, ahead of the plebiscite of 21–22 October.

Since 1866 the palace has belonged to the city, and after a full restoration it now houses the offices of the Venice Biennale, the exhibition body founded in 1895. The building is a working headquarters rather than a museum: its rooms serve the organisation that stages the Art Biennale and other international shows.

The palace sits between Hotel Bauer and Hotel Monaco and is easily visible from the Grand Canal. Inside, visitors find multiple exhibition spaces, a bookshop, and a cafe overlooking the water.

The Sala delle Colonne displays Murano mirrors and colorful stucco decorations that show Venetian design patterns from the 1700s. These interiors reveal craftsmanship and design preferences from that period that visitors often overlook.