They tower over urban landscapes, spread across city blocks and span mountainous regions, each a modern marvel of technological innovation. But how are the world's most remarkable superstructures built? This series showcases key aspects, with footage filmed during construction along with CGI to reveal building processes with astonishing detail. Take, for example, the 71,000 seat Mercedes-Benz Stadium in Atlanta. The $1.4 billion stadium is hailed as an architectural wonder because of its eight-petal retractable roof. Other episodes include a look at a cruise ship that holds more than 7,000 passengers and crew members; a flood barrier in Venice designed to prevent the ancient city from sinking into the ocean; an ambitious circular subway system running directly underneath Copenhagen, Denmark; and the world's longest suspension bridge ever built in the Arctic Circle.