Pennsylvania Avenue National Historic Site is a National Historic Site in the city of Washington, D.C. Established on September 30, 1965, the site is roughly bounded by Constitution Avenue, 15th Street NW, F Street NW, and 3rd Street NW. The historic district includes a number of culturally, aesthetically, and historically significant structures and places, including Pennsylvania Avenue NW from the White House to the United States Capitol, the Treasury Building, Freedom Plaza, Federal Triangle, Ford's Theatre, the Old Patent Office Building, the Old Pension Office Building, which now houses the National Building Museum, Judiciary Square, and the Peace Monument.

Pennsylvania Avenue is a primarily diagonal street in Washington, D.C. that connects the United States Capitol with the White House and then crosses northwest Washington, D.C. to Georgetown. Traveling through southeast Washington from the Capitol, it enters Prince George's County, Maryland, and becomes MD Route 4 and then MD Route 717 in Upper Marlboro, and finally Stephanie Roper Highway.