Image by Walter Bibikow Getty Images

Home to the UN since 1966, the Palais des Nations was built between 1929 and 1936 to house the now-defunct League of Nations. Visits are by guided tour (bring photo ID; no reservation required for groups less than 15 people) and include a one-hour tour of the building and entry to the surrounding 46-hectare park, generously peppered with century-old trees and peacocks. Spot the grey monument coated with heat-resistant titanium, donated by the USSR to commemorate the conquest of space.