Washington DC, USA

The city that runs the world's most powerful country — where the Smithsonian's 19 free museums hold everything from the Wright Brothers' Flyer to the Hope Diamond, the National Mall's 1.9 miles of monuments connect Lincoln to the Capitol, and the Library of Congress holds 174 million items in 838 miles of shelves

Washington DC (700,000; metro 6.4 million) is the capital of the United States and one of the most visited cities in North America — not primarily because of government (most government buildings are restricted) but because of the Smithsonian Institution, the world's largest museum and research complex, whose 19 museums and galleries on and around the National Mall are all permanently free. The National Mall (1.9 miles from the Lincoln Memorial to the Capitol Building) is one of the most symbolically loaded public spaces in the world — the site of Martin Luther King Jr.'s 'I Have a Dream' spe…

Washington DC was established by the Constitution of 1787 as the permanent seat of the US federal government — the ten square miles of the District of Columbia were carved out from Maryland and Virginia, selected by President George Washington (the only city named for a sitting president), and designed by French engineer Pierre Charles L'Enfant in 1791 with broad diagonal avenues, traffic circles, and the Capitol Building at the symbolic centre. The British Army burned the US Capitol and the White House during the War of 1812 (August 1814) — one of only two times in history that Washington DC…