Stansted Airport challenged all the accepted rules of airport terminal design. It went back to the roots of modern air travel and literally stood conventional wisdom on its head. The earliest airport buildings were very simple: on one side there was a road and on the other a field where aircraft landed into the wind. The progression from landside to airside was a walk from your car through the terminal and out onto your plane, which was always in view. Revealed through every aspect of its design, Stansted was an attempt to recapture the clarity of those early airfields, together with some of the lost romance of air travel. From the traveller's point of view, movement through the completed building is straightforward and direct - Stansted has none of the level changes and subsequent orientation problems that are typical to most airports. Passengers proceed in a fluid movement from the set-down point through to the check-in area, passport control and departure lounges, where they can see the planes. From there, an automated transit system takes them to satellite buildings to board their aircraft. This degree of clarity was achieved by turning the building ‘upside down’, banishing the heavy environmental service installations usually found at roof level to an undercroft that runs beneath the entire concourse floor. This subterranean level also contains baggage handling and was able to accommodate a mainline railway station, which was integrated into the building late in the design process. All service distribution systems are contained within the ‘trunks’ of the structural ‘trees’ that rise up from the undercroft through the concourse floor. These trees support a lightweight roof that is freed simply to keep out rain and let in light. Entirely daylit on all but the most overcast of days, the constantly changing play of light gives the concourse a poetic dimension and also has significant energy and economic advantages, leading to running costs half those of any other British terminal. Energy efficient, environmentally discreet within its rural setting, technologically advanced yet incredibly simple to use and experience, Stansted has become a model for airport planners and designers around the world.