The show kicks off with a dynamic taster of what the series has in store - namely the inside story of a crack team building a trailblazing, fully-automated metro system costing $50 billion.

We check in on our engineers encountering all manner of issues tunnelling through a minefield of existing infrastructure - skyscraper footings and basements, sewers, a graveyard, and rail tunnels.

Another super challenge looms, perhaps the greatest of the entire project - digging two tunnels beneath Sydney Harbour.

We follow architect Ross de la Motte, seeing that his vision for the stations has finally come to light. He has gone to great lengths to design stations that benefit from natural light and airflow.