'…the sea can never be taken for granted, and the Venetians knew it. As early as 1106, a disastrous flood had completely engulfed the old town of Malamocco, seven hundred years later its ruined houses and churches could still be discerned at low tide. … the Magistrato alle Acque, [was] the government official responsible for the proper management of the lagoon waters, …With the downfall of the Republic the Magistratura alle Acque ceased to exist and, during the long sad years of Austrian dominion that followed, the Murazzi (ancient sea walls) were neglected and many of the lagoon's secrets were forgotten. … the sea gave her [Venice] little trouble until around the end of the Second World War. …

In the 1930's, the sight of the Piazza under water was a rare thing indeed; by the 1950's it was all too common. … on 4 November 1966, the tide level rose to six feet, more than fifteen inches higher than at any time in the preceding century. …The city escaped - though only just - the fate of old Malamocco; but according to at least one informed estimate, it aged some two centuries overnight. …In December 1979, with the tide once again approaching the six-foot mark, many [of them] feared that the 1966 level would be surpassed; it seemed almost a miracle when the wind suddenly turned and the waters began to subside. Next time, however, they may not be so lucky.'

From the introduction by J.J. Norwich to Peter Lauritzen's book, 'Venice Preserved' published by Michael Joseph.