The Archaeological Museum of Torcello adds context to the quiet lagoon island, with Greek and Roman pieces and finds from the Venetian estuary's Paleo-Veneto and Etruscan periods. It is a small museum, but useful if Torcello's empty fields and old cathedral have made you curious about the island's earlier life.
See it together with the cathedral and the rest of Torcello rather than making a separate trip just for the collection.