For two years, we’ve followed construction of the new California Department of Transportation headquarters in downtown LA–a massive 700,000 square-foot office building–and we use this building as a specific example to illustrate construction problems of mega-skyscrapers, from the Empire State Building to the Sears Tower to the TAIPEI 101. In hour two, the steel skeleton is up, but before the windows and walls go up, the general contractor tests the exterior wall system by building a mockup.