Submergence of historical sites through dams

Many of Rome's ancient structures, such as the Bridge of Cestius (Ponte Cestio), first built in 62 BC, are threatened by undercutting by the River Tiber. The cause is the construction of hydroelectric dams upstream which have blocked the flow of sand and silt that renew the river's bed.

A dam being constructed on the third longest river in the world, the Yangtze in China, threatens to submerge around 1,300 sites of historical and archaeological interest, with only the most high-profile sites likely to be rescued in time.