Plot: For two years, we’ve followed the construction of the new California Department of Transportation headquarters in LA to learn the architectural, structural, and mechanical challenges of building mega-skyscrapers. In hour four, as we’re installing the veins and arteries of the building and wrapping up construction on CalTrans, we learn how development of electricity and indoor plumbing made skyscrapers possible–imagine needing to take an elevator down 70 stories to use the privy behind the building!