The Cathedral of Santa Maria Assunta (Cattedrale di Santa Maria Assunta) is a basilica church on the island of Torcello, Venice, northern Italy. It is a notable example of Venetian-Byzantine architecture, one of the most ancient religious edifices in the Veneto.
According to an ancient inscription, it was founded by the exarch Isaac of Ravenna in 639.
The original church is believed to have had a nave with one aisle on each side and a single apse on the eastern wall of the cathedral. It is difficult to tell what the original church was like because very little of it survived the subsequent renovations. Much of the plan of the original church survives as its present form is very similar to the original but the only physical parts that survive are the central apse wall and part of the baptistery that survives as part of the façade of the current church.
The first of two major renovations occurred in 864 under the direction of Bishop Adeodatus II. In this renovation, the two aisle apses that appear today were built. Also, the synthronon that fills the central apse was created and the crypt was placed under it. After this renovation, the cathedral would have resembled the current cathedral more than the original church would have but it is not until after the second and final major renovation that the cathedral appears very similar to its current design.
The final renovation was consecrated under Bishop Orso Orseolo, whose father Pietro Orseolo II was the Doge of Venice at the time, in 1008. With this renovation, Orseolo raised the nave, added windows to the western wall, and created the arcade that runs along the nave on both sides separating it from the aisles and helping to support the clerestory.
The façade is preceded by a narthex to which was once annexed the 7th century baptistry, only traces of which remain. On its side is the martyrion, dedicated to Santa Fosca. The bell tower dates from the 11th century. Also annexed was in origin the Bishop's Palace. The façade has 12 semi-columns connected by arches at the tops. The narthex (11th century) was enlarged in the 13th century. In the middle is the marble portal (1000).
The most striking exterior features are the decoration of the façade and the frontal portico, enlarged in the 14th century. The interior, with a nave and two aisles, has a marble pavement, the throne of the bishops of Altino and the sepulchre of St. Heliodorus, first bishop of Altino. The counter-façade has a mosaic of the Universal Judgement. Noteworthy is also a mosaic depicting a Madonna with Child (of the Hodegetria type) in the middle apse (15th century).
The most important artistical element of the cathedral is a series of mosaics of Byzantine-Ravennate school, including a Last Judgement in the counter-façade. The skull of Saint Cecilia is also kept as a relic here.