Turism is the second most important aspect of the city's economy. The historical monuments sightsee more than 18 million visitors each year. The tourism industry have created a large service economy, which employs over one-third of all Washington's workers. In the city are three commercial airports—Washington National, Dulles International, and Baltimore-Washington International.
Universities in Washington include Georgetown University (1789), American University (1893), George Washington University (1821), the Catholic University of America (1889), Trinity College (1897), Howard University (1867), and Gallaudet University (1856).
In the city are the Vietnam Veterans Memorial (1982) and the Vietnam Women's Memorial (1993), the Thomas Jefferson Memorial (1943), the Lincoln Memorial (1922), and the Washington Monument (1884), a 169-m (555-ft) obelisk.



The most conspicuous structure in Washington, because of its majestic architecture and vantage point on a hill, is the Capitol of the United States. In front of the Capitol are the Supreme Court Building (1935) and the main Library of Congress. About 2.4 km (1.5 mi) west of the Capitol is the White House (begun 1792, rebuilt after 1814). Initially named the President's House, it was first occupied by President John Adams and has been the home of every US president since. The White House fronts on Lafayette Square, and the rear balcony looks out across the Ellipse, past the Washington Monument, to the Jefferson Memorial. Directly west is the Executive Office Building (1871-1888), which houses the president's staff.