It's not the world's biggest dam, but it was the one that changed the way we build them.
The first of the large concrete arch dams that dominated the 20th century, Hoover also marked the birth of America's dam-building boom. Its Depression-era construction cost $49 million and used so much concrete that engineers had to pipe cooled river water through the dam face to help the concrete cool faster.
The sweeping, 60-story-high concrete arch, along with its water works, power station and intake towers, were all designed in classic art deco style, reminding us of the days when plans for public works projects included intricate stone and metalwork, ornate plaques, and elegant statues of massive seraphs guarding the gates. They just don't build them like they used to.
PUZZLES: Feats of Engineering Puzzles
