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
Leipzig/Halle Airport the airport for NATO and EU military aircraft. The airport was built new from scratch at a location between Halle and Leipzig from 1926 and opened in 1927. On 18 March 1986 Air France flew a Concorde to the airport, to coincide with the world-renowned Leipzig trade fair. Two days later British Airways also flew a Concorde to Leipzig/Halle. In the following years, both airlines operated Concorde flights from Paris and London when the trade fair was held in Leipzig. Despite its name, the airport ground property tax goes to the county of Delitzsch. A deal between the city of