The Fortezza is the Venetian-era citadel of the city of Rethymno in Crete, Greece.
In the aftermath of the fall of Cyprus to the Ottoman Empire in 1571, the Venetians began fortifying Crete, their largest remaining overseas possession. Construction began on 13 September 1573. The fortress was conquered by the Ottomans in 1646, and remained in use until the early 20th century. During Ottoman times, most of the space inside the fortress was settled, and the last houses were demolished only in the 1960s. Large-scale restoration work is under way since the early 1990s.
The Fortezza is the citadel of the city of Rethymno. By the early 20th century, many houses were built within the citadel. These were demolished after World War II, leaving only a few historic buildings within the Fortezza. Today, the citadel is in good condition and is open to the public. It is built on a hill called Paleokastro (meaning "Old Castle"), and a number of buildings are located within it, including the churches of St. Theodore and St. Catherine, which were both built in the late 19th century.