Venice, which rests on millions of wooden piles pounded into marshy ground, has sunk by about seven centimetres a century for the past 1,000 years.
(According to a study done in 2000 and reported by CNN)
The earth's natural underground water supplies acted as a cushion that helped slow the city's sinking.
Venice and its lagoon was added to UNESCO’s World Heritage list in 1987.
The Italian government is spending 4.5bn euro (£2.9bn) on a controversial project to build floodgates across the entrance to the lagoon in which the city stands in an effort to keep the sea at bay.