The 23 km Green line of the Dubai Metro opened in September 2011, exactly 2 years after the 52 km Red line, making it the world's longest driverless metro. In a city dominated by the car but projecting heavy population growth, the metro has been designed to provide unparalleled levels of customer comfort and finishing, together with the frequency, punctuality and coverage to meet the emirate's future strategic needs and ambitions. This paper provides an overview of the £4·8 billion project, with particular emphasis on the heavy civil engineering solutions delivered within a highly stylised and exacting architectural context, from an outline plan in 2002 to a fully operational reality in 2011.