The District of Columbia, often referred to as Washington, D.C., is the capital of the United States. It is a federal district, meaning it is not part of any state and was established to serve as the nation's capital. The area was selected in 1790 and is located along the Potomac River, bordered by the states of Maryland and Virginia. Washington, D.C. is home to many important government buildings, including the White House, the U.S. Capitol, and the Supreme Court. The district also features numerous museums, monuments, and memorials, such as the Lincoln Memorial and the Smithsonian Institution, making it a significant cultural and historical center.