The Hoover Dam

The Hoover Dam on the Nevada-Arizona border was the largest dam in the world when it was completed in 1935, standing 726 feet tall and containing enough concrete to build a two-lane highway from San Francisco to New York. The construction killed 112 workers in officially documented deaths, though the actual number is believed to be higher. The project was completed two years ahead of schedule. Lake Mead, the reservoir it created, was the largest artificial lake in the world for many years. Today the lake sits at roughly a third of its historic capacity due to decades of drought.

Source: Wikipedia