There are legends about Venice more than enough. These are the facts so far:
• Early settlements were dated to the Roman period. The sea forced the settlers to not to settle in flooded areas. (Severe flooding was there the 4th and 5th, then in the 9th and in the 11th - 13th century).
The municipality Rivoalto (civitas Rivoalti) was attached to the center (castrum), which was surrounded by agricultural settlements. The designation of places as fields (campi) or small fields (campielli) thus goes back to an agricultural tradition. Even the city structure followed a grid that corresponds to the Roman land division.
The problem of the origin of Venice is about the question of continuity between roman and medieval times. (Excavations at Torcello)
Venice therefore belonged to the Byzantine sphere of influence, was subordinate to the governor (exarch) of Ravenna and became independent only because of its increase in power at a later date.
Venice, before it existed at all, the province of Venice on the mainland, the 10th region of the Roman Empire, was already populated. As Altino and Concordia went down, large groups of refugees sought shelter in the coastal and lagoon areas. (Grado, Caorle, Chioggia)
Venice used its marginal position in the Eastern Roman Empire and achieved an increasingly extensive autonomy.