Walls, towers and gates Torre e Forte San Erasmo Sant'Erasmo is the second largest island in the lagoon. The Massimiliana Tower, located in Sant'Erasmo, was built by the Austrians between 1843 and 1844. The Massimiliana Tower has a circular structure surrounded by a moat and an irregular polygonal embankment. It is the only example in Italy that hosts art exhibitions, photography and various cultural events.