San Giorgio in Alga
St George of the Seaweed
Located between the Giudecca and Fusina, this was one of the many islands in the lagoon colonized by monks, in this case Benedictines in the early 11th century, They were followed by the Augustian canons, who arrived in 1404, seeking a contemplative life. One of the first to arrive was the future saint, Lorenzo Giustiniani, from one of Venice's great families, who became Prior General of the order.
The Augustinians eventually declined, and departed for good when their buildings caught on fire in 1717. There were several palaces as well, and in one, Doge Renier held a magnificent ceremony to greet Pope Pius VI in 1782. The island was later used as a political prison until the 19th century, and last used as a secret Nazi military base during the war, where frogmen were taught how to lay mines by night.
Since then it's been left a romantic abandoned ruin, and only accessible by private transport.