I saw part of a documentary about the Millau Viaduct. When I first heard about before it was being built, it was hard to picture it. It was HUGE, and push the parts out... and the height? It was just too big.
Something that was pretty cool to see was when they built the bridge, Öresundsbron (8km bridge + 4km tunnel, top level is a a 4 lane road, lower level has 2 train tracks), between Sweden and Denmark. When it was finished 1999 it was the longest of its kind, not sure if it is anymore. But the boat crane they used was enormous. It's still sitting in the harbor here.
They built the sections on land and we're not talking small sections, then they were taken out to the bridge by the boat crane and put into place. The foundation sections were also put into place by the crane.
The crane is called Svanen and can lift 8700 tonne.
http://www.leopoldreport.com/Bro0814.html
One pic of it at the bottom of the page
http://www.svt.se/malmo/oresundsbron/dokument/dokum.htm
http://www.svt.se/malmo/oresundsbron...ent/vatten.htm
One my favorite pics of the bridge

It's taken from the nude bath house hehe.