Washington's sights divide between the free national institutions of the National Mall and the city's own neighbourhoods and history. Allow at least three to four days to do justice to both.
The Mall's free Smithsonian museums include the National Gallery of Art, the National Air and Space Museum, the National Museum of Natural History, the National Museum of the American Indian, the Hirshhorn Museum, the Freer and Sackler Galleries, the National Museum of African American History and Culture, and others.
The memorials and monuments — all free and open 24 hours — include the Lincoln Memorial, Vietnam Veterans Memorial, Washington Monument, Jefferson Memorial, Martin Luther King Jr. Memorial, Korean War Veterans Memorial, and the World War II Memorial.
Beyond the Mall: Georgetown for walking and the C&O Canal; Dupont Circle for the Phillips Collection and bookshops; Capitol Hill for the Eastern Market, Library of Congress, and Victorian streetscapes; Adams Morgan for Ethiopian food and neighbourhood vitality. The US National Arboretum and Rock Creek Park offer green space outside the formal monument circuit.
Across the Potomac in Virginia: Arlington National Cemetery for the Tomb of the Unknown Soldier and Kennedy graves.