A fascinating exploration of the global phenomena of skyscrapers over 300 m tall with engineer Rob Bell. From the world's tallest building to those currently under construction, Rob goes on a journey across two episodes to uncover the secrets of these giants, from the foundations that lie below ground, to the colossal structures above ground and the invisible forces that shape them. Revealing the secrets of the inner workings from lifts to power and water supplies Rob examines the engineering challenges that have to be overcome to be able live and work at such height, and explores the visions of the future for these cities in the skies.