Transport in Hamburg comprises an extensive, rail system, subway system, airports and maritime services for the more than 1.8 million inhabitants of the city of Hamburg and 5.3 million people in the Hamburg Metropolitan Region. Since the Middle Ages, as a Hanseatic City one part of Hamburg's transport was the economic trade with other cities or regions. In 2008, the port of Hamburg was the second-largest port in Europe. Hamburg is connected to four motorways and in Hamburg proper are two airports. The Hamburg traffic group Hamburger Verkehrsverbund was the first organisation of its kind in the world and in 2008, was in charge for the public transport management in three German states. In 2007, more than 618 million passengers used bus, rapid transit, ferries or light rail. History A charter in 1189 by Frederick I, Holy Roman Emperor granted Hamburg the status of a free imperial city and tax-free access up the Lower Elbe into the North Sea, the right to fish and to cut trees, and the freedom of military service. The charter was given orally for Hamburg's backing of Frederick's crusades, and in 1265 an in all probability forged letter was presented to or by the Rath (Council; Rat in antiquated writing style) of Hamburg. In 1241, the two contracts between Hamburg and Lübeck marked the beginning of the Hanseatic League, a trade union in Northern Europe. And in 1264 the Steinstraße was the third cobbled road in Europe, the east-west route for commerce. In 1800 Hamburg has 1,473 street-lamps and on the Hamburg hill in St. Pauli several new streets were given Christian names e.g. Davidstraße, Erichstraße or Herbertstraße. On 31 October 1839, the first horse-drawn bus line served a scheduled route from Hamburg to the then Danish Altona. In 1866, the Hamburg tramway network was opened. Initially, it was operated with horsecar trams. In 1894, Hamburg's first electric tram served Meßberg – Lombardsbrücke – Landungsbrücken – Zollkanal – Meßberg. In 1906, the Hamburg Hauptbahnhof was built and the rail lines—like the Rollbahn line—were expanded into the city centre, and in 1910 a hall for the air traffic with zeppelins was built in Fuhlsbüttel. 1911, the first tunnel under a river in continental Europe was finished, and Benzindroschken (gasoline-run vehicles) were allowed on Hamburg's streets. In 1912, the port of Hamburg provided 64 km moorings for more than 15,000 seagoing vessels, arriving in Hamburg. The Hamburger