The new federal territory was named District of Columbia to honour explorer Christopher Columbus, and the new federal city was named for George Washington.   Washington, DC, anchors the southern end of the Northeast megalopolis, one of the nation's largest and most influential cultural, political, and economic regions.   As the seat of the US federal government and several international organizations, the city is an important world political capital.   The city was founded in 1791, and the 6th Congress held the first session in the unfinished Capitol Building in 1800 after the capital moved from Philadelphia.   In 1801, the District of Columbia, formerly part of Maryland and Virginia and including the existing settlements of Georgetown and Alexandria, was officially recognized as the federal district; initially, the city was a separate settlement within the larger district.   In 1846, Congress returned the land originally ceded by Virginia, including the city of Alexandria.   Designed in 1791 by Pierre Charles L'Enfant, the city is divided into quadrants, which are centered around the Capitol Building and include 131 neighborhoods.   The Washington metropolitan area, which includes parts of Maryland, Virginia, and West Virginia, is the country's seventh-largest metropolitan area.

The city hosts the US federal government and the buildings that house government headquarters, including the White House, the Capitol, the Supreme Court Building, and multiple federal departments and agencies.   The city is home to many national monuments and museums, located most prominently on or around the National Mall, including the Jefferson Memorial, the Lincoln Memorial, and the Washington Monument. It hosts 177 foreign embassies and serves as the headquarters for the World Bank, the International Monetary Fund, the Organization of American States, and other international organizations.   Many of the nation's largest industry associations, non-profit organizations, and think tanks are based in the city, including AARP, American Red Cross, Atlantic Council, Brookings Institution, National Geographic Society, The Heritage Foundation, Wilson Center, and others.   The city is known as a lobbying hub, with K Street as the center of such activities.

Many of the government buildings, monuments, and museums along the National Mall and surrounding areas are heavily inspired by classical Roman and Greek architecture.   The designs of the White House, the U.S. Capitol, Supreme Court Building, Washington Monument, National Gallery of Art, Lincoln Memorial, and Jefferson Memorial are all heavily drawn from these classical architectural movements and feature large pediments, domes, columns in classical order, and heavy stone walls.   Notable exceptions to the city's classical style architecture include buildings constructed in the French Second Empire style, including the Eisenhower Executive Office Building, and the modernist Watergate complex. The Thomas Jefferson Building, the main Library of Congress building, and the historic Willard Hotel are built in Beaux-Arts style, popular throughout the world in the late nineteenth and early twentieth centuries.   Meridian Hill Park contains a cascading waterfall with Italian Renaissance-style architecture.

The Washington Metropolitan Area includes all of Washington DC and parts of Maryland and Virginia.   It is part of the larger Washington–Baltimore combined statistical area, which is the third-largest combined statistical area in the country with a population of over 6 million.   Cities included in the area are Arlington, VA - Alexandria, VA - Dale City, VA - Centreville, VA - Reston, VA - Leesburg, VA - Manassas, VA - Fredericksburg, VA - Tysons, VA - Germantown, MD - Silver Spring, MD - Waldorf, MD - Frederick, MD - Gaithersburg, MD - Rockville, MD - Bethesda, MD - Bowie, MD.