Concourse B (right side of photo) opened with 20 gates in 1998 so more planes could be accomodated at airline gates. It would later be expanded further to the west. Photo from August 2001.

In 2001, work began on a 4-gate addition to the western end of Concourse B. Photo from November 2001.

Aerial view of 4-gate addition under construction in foreground, circa 2002.

Concourse B is built with modular window panels, which allow for flexibility in the positioning of gates and doorways. Photo from February 2002.

Interior view of 4-gate addition to Concourse B under construction. Photo from February 2002.

Further growth at Dulles prompted the need to expand Concourse B an additional 15 gates (lower right part of photo). Included in this project is a train station below the Concourse (left side of photo). Photo from April 2006

This photo shows the western Concourse B AeroTrain station (left) in an early phase of construction, with the Concourse B expansion at right. Photo from March 2006.

The foundation of the Concourse B 15-gate expansion begins to take shape. The western end of the existing Concourse is visible in the background Photo from March 2006.

Concourse B is visible at the lower right, looking west to the expansion and its associated construction cranes. Photo from August 2006.

The Concourse B expansion is visible from the windowall at the west end of Concourse B. Photo from August 2006.

Looking out the western end of Concourse B to view the 15-gate expansion under construction. Photo from August 2006.

Side view of the steel framework for the Concourse B 15-gate expansion. Photo from September 2006.

Looking down the center of the Concourse B expansion, with west end of existing Concourse B in the background. Photo from September 2006.

Looking west to view the Concourse B expansion from high above the AeroTrain station that will connect to the existing Concourse. Photo from October 2006.

The interior of the Concourse expansion begins to take shape. It is modeled after the rest of Concourse B. Photo from March 2007.

Good aerial view of the Concourse B expansion, the Concourse B AeroTrain station, and existing Concourse B as of May 2007.

Progress continues on the interior. Photo from August 2007.

This is the retail court directly above the Concourse B AeroTrain Station. Photo from August 2007.

A temporary passageway links passengers between the existing Concourse B and the expanded section. Construction of a retail court and train station continued outside the passageway. Photo from December 2007.

The final touches are applied to the Concourse B expansion just days before opening. Photo from January 2008.

Construction progress continues on the retail court which connects the extension to the rest of Concourse B. Passengers used the passageway shown in the lower right of the picture. Photo from May 2008.

Interior view of the temporary passageway through the retail court. The passageway connects the Concourse B expansion with the rest of Concourse B. Photo from May 2008.

Exterior photo showing the Concourse B Expansion at Washington Dulles International Airport. Photo from May 2008.

Aerial view of Concourse B at Dulles with the 15-gate expansion in the foreground. Photo from May 2008.

Aerial view of the 15-gate expansion of Concourse B with the Dulles Main Terminal visible in the background. Photo from May 2008.