Frankfurt is served very well by rail, road, river transport and has the third busiest airport in Europe (Frankfurt Flughafen AG - 40 million passengers in 2000). Many international companies have chosen the city for their headquarters, including Aventis (chemical/pharmaceutical), Hoechst, Degussa-Hüls, Opel (Rüsselsheim), the Philipp Holzmann building company.
The city has been known since medieval times for it's trade fairs and hosts many international events each year. Perhaps the most well-known is the Frankfurt Book Fair, which with over 100000 visitors is probably the largest of it's kind in the world. The Frankfurt Motor Show is an important showcase for the automotive industry and includes the launches of many new models from the world's foremost auto manufacturers.