Filter through the technological leaps forward that have allowed the world's largest hydroelectric dam - the Three Gorges Dam in China - to be built. The Dam harnesses the power of China's great Yangtze River. It is over two kilometres long, towers over 60 storeys high and creates a reservoir 600 kilometres in length. On completion the scheme will be able to generate 22,500 megawatts of power - enough to supply electricity to 60 million people. At its peak, over 25,000 men and women were working round the clock to make what was once Chairman Mao's dream a reality. Explore how this immense project was made possible through a series of breakthroughs on six landmark dams - including the Hoover Dam in America. Each features a major technological innovation that allowed engineers to create bigger dams to generate ever more hydroelectric power.

• John Michie
• Rick D. Wasserman