The Dulles International Airport Main Terminal is located in Loudoun and Fairfax counties in Dulles, Virginia, United States. The original structure, 600 feet (180 m) long and 150 feet (46 m) wide, was designed by Eero Saarinen and completed in 1962 as the first terminal at Dulles International Airport. Annexes to the west and east were completed in 1996 as part of a renovation designed by Skidmore, Owings & Merrill (SOM), bringing its total length to 1,240 feet (380 m). The terminal is operated by the Metropolitan Washington Airports Authority, which operates Dulles Airport as a whole. The terminal's design is a suspended structure with roof panels of precast concrete suspended between cables which span the width of the building.
The Main Terminal's design includes parallel slanted colonnades on the terminal's north and south facades, interspersed with glass walls. The landside facade to the north is taller than the airside facade to the south; a concave roof supported by cables connects the two facades, descending toward the center. A concourse and control tower extend south toward the airport's apron. The interior was originally divided into two levels: an upper story for departing passengers and a lower story for arriving passengers. Saarinen's original design included mobile lounges that ferried passengers directly to planes, reducing the need for long walks or taxiing while increasing the airport's operational flexibility. The modern terminal includes four airline gates known as Z gates, where aircraft could unload passengers directly. In addition, two basements contain security screening facilities and an AeroTrain people-mover station.
