Reputed to be the largest Venetian castle ever built, the Venetian Fortalezza at Rethymno was designed to shelter the entire population. In the 15th century, armies began using gunpowder in military activities, which prompted the design of forts which could withstand this type of attack. The Venetians did not have the funds to complete the Fortezza according to the new formula for defensive structures, and allowed the houses of the town to remain close to the walls, leaving no distancing space or room for a moat. This, as well as other factors, including a cholera epidemic in the fort, led to an easy victory for the Turkish invaders in 1645.
The fort has a commanding view of the harbor and the town: