The Tiepolo bastion on the southwestern side of the island is named after the Venetian Duke Almorò Tiepolo, while it is also known as the Riva bastion, a name deriving from the Provisioner of the fortress, Giacomo Da Riva. It is the largest among the bastions of the fortress and is constructed during the initial building phase (1579-1584). Its original form is hard to document due to the numerous alterations made over the years. During the Cretan War (1645-1669), the low square of the bastion was infilled, and as a result, its closed cannon port opening is enclosed. New open cannon ports are built to defend the fortress sufficiently.

In the interior of the bastion, there are also vaulted spaces, which are later converted into a reservoir for collecting rainwater. During the operating period of the Leper Colony, the open cannon ports are removed to create dormitories, which, however, are demolished from 1979-1981.