his two part series looks at the most impressive manmade structures in the USA. Behind each of them is a big story of an engineer's vision, a daring plan, of problems overcome or disasters that befell. Eye-popping aerial photography is allied to state-of-the art computer graphics to show these icons of architecture rise up girder by girder, block by block. The Empire State Building is actually rebuilt floor by floor, and the Kennedy Space Center rises from an alligator-infested swamp, while giant faces are carved out of the bare mountain at Mt Rushmore.