Federal Triangle station in the context of "Washington Metropolitan Area Transit Authority"

Federal Triangle is a triangular area in Washington, D.C., formed by 15th Street NW, Constitution Avenue NW, Pennsylvania Avenue NW, and E Street NW. Federal Triangle is occupied by 10 large city and federal office buildings, all of which are part of the Pennsylvania Avenue National Historic Site. Seven of the buildings in Federal Triangle were built by the U.S. federal government in the early and mid-1930s as part of a coordinated construction plan that has been called "one of the greatest building projects ever undertaken". Two buildings predating this coordinated effort were incorporated into Federal Triangle, and one was constructed in the 1990s.

Federal Triangle station is the Washington Metro station serving Federal Triangle and its immediately surrounding areas.

The Old Post Office, listed on the National Register of Historic Places as the Old Post Office and Clock Tower, is located at 1100 Pennsylvania Avenue, N.W. in Washington, D.C. It is a contributing property to the Pennsylvania Avenue National Historic Site. It is adjacent to the Federal Triangle station on the Washington Metro. The building's 315-foot (96-meter) high clock tower houses the "Bells of Congress," and its observation level offers panoramic views of the city and its surroundings. A historic federal office building, it now serves as a hotel.

Construction began in 1892 and was completed in 1899. The building is an example of Richardsonian Romanesque architecture, popular in the late 19th-century United States. Its bell tower is the third tallest structure in Washington, D.C., excluding radio towers. It succeeded an earlier 1839 building, the General Post Office, which was built in Classical Revival style on F Street NW. It was used as the city's main General Post Office until 1914 at the beginning of World War I.