The Great Boulder Dam, Boulder City, Nevada, U.S.A. -- Upstream face of Boulder Dam dedicated 30th Sept. 1935 Work is still in progress on the power plant. The Boulder Dam, a towering 700-feet wall of concrete built across the turbulent waters of the Colorado River, has been constructed at a cost of more than ?24,000,000 and is America's greatest engineering feat since the Panama Canal. It will develop 2,000,000 hors power and will be the largest artificial lake in the world. The water from the reservoir will be piped 250 miles to the coast cities through huge aqueducts. It was dedicated by president Roosevelt at the end of September. December 30, 1935. (Photo by Sport & General Press Agency, Limited).