London

London needs 4 days: Buckingham Palace and Westminster on one, the Tower of London and Tower Bridge on another, the British Museum on the third, and Camden or Notting Hill on the fourth. March-May avoids winter cold and summer crowds. It's expensive, among the world's priciest cities, though many major museums have free admission. It's one of the world's most multicultural cities, with over 300 languages spoken, and its combination of a living monarchy, millennia-old history and contemporary cultural scene has no exact equivalent in any other capital.