Paris for 31 percent of the GDP of France. According to the Economist Intelligence Unit Worldwide Cost of Living Survey in 2018, Paris was the second-most expensive city in the world, behind Singapore and ahead of Zurich, Hong Kong, Oslo and Geneva. The city is a major rail, highway, and air-transport hub served by two international airports: Paris-Charles de Gaulle (the second busiest airport in Europe after London Heathrow Airport with 69.5 million passengers in 2017) and Paris-Orly. Opened in 1900, the city's subway system, the Paris Métro, serves 5.23 million passengers daily, and is the second busiest metro system in
Paris–Le Bourget Airport crossing in 1927 in the "Spirit of St. Louis", and had been the departure point two weeks earlier for the French biplane "The White Bird (L'Oiseau blanc)", which took off in its own attempt at a transatlantic flight but then mysteriously disappeared. On 25 June 1940, Adolf Hitler began his first and only tour of Paris, with Albert Speer and an entourage, from Le Bourget Airport. On 16 June 1961, the Soviet ballet dancer Rudolf Nureyev defected at Le Bourget Airport. In 1977, Le Bourget was closed to international airline traffic and in 1980 to regional airline traffic, but remains