The capital of the United States of America, its abbreviation is a shorthand for “Washington, District of Columbia”. It is filled with museums and monuments. The White House, the manse reserved for the President/Administrations, is located here, along with Congress.
The District of Columbia, as a neutral territory for putting the capital in, was a rectangle carved from Maryland and Virginia; however, Virginia later took its contribution back, hence why it now has an irregular border on the south side. D.C. is also noted for its residents not having the same voting rights as elsewhere in the U.S., and for a law banning handguns that is usually mentioned in the ubiquitous gun control “debates” on the board.
If you're from here, feel free to add yourself to the list.