Imagine driving across a bridge near the North Pole, leaving Alaska at one end and arriving in Siberia at the other end; or visiting a city built within a pyramid in Tokyo Bay; or speeding from New York to London in just an hour through a tunnel under the Atlantic Ocean. These are just some of the projects that come to life as builders and engineers design and construct the largest, most outrageous and awe-inspiring projects ever conceived. Jaw-dropping computer. Episode 8: The Hong Kong international airport is the largest civil engineering project in history and the largest enclosed space in the world. It is also 16 miles out to sea and built on a platform that was constructed by leveling two small islands.