Federal Triangle, Government complex in downtown Washington, United States.

Federal Triangle is a triangular government complex in downtown Washington, D.C., bounded by Constitution Avenue, Pennsylvania Avenue, and 15th Street. It houses ten major federal administration buildings, including the Departments of Justice and Commerce and the Environmental Protection Agency.

The Public Buildings Act of 1926 authorized construction of the Federal Triangle and marked the transformation of a deteriorated neighborhood into a government center. Construction began in the late 1920s and reshaped downtown Washington's appearance for decades to come.

The name "Federal Triangle" came from journalism: the press wrote of a "Pennsylvania Avenue Triangle" in 1926, and the Associated Press first used "Federal Triangle" in 1935. The complex is part of the Pennsylvania Avenue National Historic Site, and the Metro station of the same name sits within it.

The area is bounded by 15th Street NW, Constitution Avenue NW, Pennsylvania Avenue NW and E Street NW, with the Metro station of the same name on the line serving it. The blocks are laid out for walking, and the long curved wings and inner courtyards mean several entrances face away from the main avenues, so check which facade you want before crossing.

The Internal Revenue Service building's cornerstone was laid in 1929 by Treasury Secretary Andrew Mellon, marking the start of construction during the Great Depression. This project became an important employment program during a time of severe economic hardship.