When Dulles International Airport opened in 1962, it was the first in the United States to be designed for commercial jet aircraft. With this challenge in mind, Eero Saarinen analyzed the problem of creating a large terminal for jet airplanes. His innovative solution was to create a compact main terminal serviced by a system of “mobile lounges” that revolutionized the airport experience. Since its completion in 1962, Dulles Airport has continued to evolve to meet the changing needs of air travel through the addition of security areas, new concourses in the midfield and expanded baggage facilities. SOM has continually worked with the Metropolitan Washington Airport Authority (MWAA) to improve the performance and operation of the airport. The most recent result of this collaboration is a Main Terminal Station and Automated People Mover System that will replace the mobile lounges as the primary means of internal transportation for passengers between the main terminal and midfield concourses. This automated train system will create a more streamlined connection, not unlike Saarinen’s original goals for the airport infrastructure. The People Mover also anticipates the further expansion of the airport as more concourses are built in the midfield and a potential south terminal is constructed. Designers seamlessly integrated the Main Terminal Station into the historic building (a nationally registered landmark) by placing the station below grade. This neutral space allows for transparency of functions and ease of circulation. Skylights admit daylight into the area, diminishing the sense of being underground. The below-grade expansion incorporates the additional security measures required by the Transportation Security Administration, including separate doors for screening. Concrete was used as the main building material, as it meets both structural and economical requirements, and contributes to the design of a timeless facility that will withstand the demands of ever-changing operational objectives.