Pennsylvania Avenue National Historic Site

On September 30, 1965, Secretary of the Interior Stewart Udall, with the concurrence of President Lyndon B. Johnson, designated the Pennsylvania Avenue National Historic Site. Encompassing the avenue between the U.S. Capitol and the White House, and a number of blocks around it, the site was added to the National Register of Historic Places on October 15, 1966.
The following GSA buildings are within the boundaries of the site:
Herbert C. Hoover U.S. Department of Commerce Building

The Herbert Clark Hoover Department of Commerce Building, with 3,300 rooms and over 1.8 million square feet of floor area, was the largest federal building in the country when it opened in 1932, and was proclaimed the largest office building in the world. The building demonstrates academically rigorous adherence to the Italian-inspired Second Renaissance Revival style with consistent cornice lines, strong horizontality, stone facing, colonnades and red tile roof.
Federal Trade Commission Building

The Federal Trade Commission Building is designed in the Classical Revival style of architecture. It is a refined style that conveys the dignity and stability of the federal government, which was particularly important during the Great Depression.
Internal Revenue Service Building

The general architectural style for the Federal Triangle was the 18th century French Renaissance style, which in turn derived its inspiration from Italian Renaissance architecture. The IRS Building is one of the more simple interpretations of this style in the Federal Triangle.
Robert F. Kennedy Department of Justice Building

The U.S. Department of Justice building retains exceptional historic integrity. The original facades, lobbies, corridors, library, Great Hall, executive suites and private offices retain their original materials and design, including the extensive use of ornamental aluminum.
William Jefferson Clinton Federal Building

Architects William A. Delano and Chester H. Aldrich created a monumental building with a semicircular facade to front the grand plaza planners envisioned for the center of the Federal Triangle. Their design was intended to rival the magnificence of public buildings in other world capitals. They drew inspiration from London County Hall and Place Vendome in Paris.
Old Post Office Building

Built from 1892 to 1899 to house the U.S. Post Office Department Headquarters and the city's post office, the Old Post Office Building remains the second-tallest structure in the nation's capital, after the Washington Monument.