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
George Bush Intercontinental Airport was the third terminal to be built at the airport, opening in 1981. It was designed by the Houston firm of Airport Architects, a joint venture of Golemon & Rolfe Architects and Pierce and Pierce Architects. Terminal C has 31 gates. The terminal includes the airport's interfaith chapel. The terminal underwent renovations from 2000 to 2005, designed by Gensler. On May 11, 2015, the airport broke ground on the airport's new Terminal C north concourse, which opened in March 2017. In March 2017 United also opened a Global Reception area for Global Services and Global First check-in which directly connects