Frankfurt is a global hub for commerce, culture, education, tourism and transportation, and rated as an "alpha world city" according to GaWC. It is the site of many global and European corporate headquarters. In addition, Frankfurt Airport is the busiest in Germany, one of the busiest in both Europe and the world, the airport with the most direct routes in the world, and the primary hub for Lufthansa, the national airline of Germany. Frankfurt is one of the major financial centers of the European continent.