The exterior facade of Union Station facing out at Columbus Circle.
Union Station was conceived as a "union" between the Baltimore & Ohio Railroad and the Baltimore & Potomac Railroad to consolidate two stations into one. This was developed in part to remove tracks from the National Mall area and showcase a grand entrance to the capital city. McMillan Commission member Daniel Burnham was appointed the lead architect after the project was approved in 1903 by President Theodore Roosevelt, and construction was completed in 1907.
This photo from the 1960s shows little changed in the Main Hall from its original layout in 1907.