Hamburg, officially Freie und Hansestadt Hamburg, is the second largest city in Germany, with a population of over 1.7 million people. The official name reflects Hamburgs history as a member of the medieval Hanseatic League, a free imperial city of the Holy Roman Empire, a city-state, and one of the 16 states of Germany. Before the 1871 Unification of Germany, it was a fully sovereign state. Prior to the constitutional changes in 1919, the civic republic was ruled by a class of hereditary grand burghers or Hanseaten. Though repeatedly destroyed by the Great Fire of Hamburg, the floods, and military conflicts including WW2 bombing raids, the city managed to recover and emerge wealthier after each catastrophe. On the river Elbe, Hamburg is a major port and a global service, media, logistics and industrial hub, with headquarters and facilities of Airbus, Blohm + Voss, Aurubis, Beiersdorf, and Unilever. The radio and television broadcaster NDR, Gruner + Jahr, and Spiegel are also based in Hamburg. Hamburg has been an important financial centre for centuries and is the seat of Germanys oldest stock exchange and the worlds second oldest bank, Berenberg Bank. With the International Tribunal for the Law of the Sea, the EU-LAC Foundation, the UNESCO Institute of Lifelong Learning, many consular and diplomatic missions and various international conferences like Hamburg Summit: China meets Europe and the 2017 G20 Hamburg summit, the city is also a factor in world politics and international law. The city is a tourist destination for both domestic and international visitors, ranked 18th in the world for livability in 2016. The ensemble Speicherstadt and Kontorhausviertel was declared a World Heritage Site by the UNESCO in 2015. Hamburg is a major European science, research, and education hub, with several universities and institutes. Its creative industries and cultural sites include the Elbphilharmonie and Laeisz concert halls, art venues, music producers, and artists. It gave birth to movements like Hamburger Schule and paved the way for bands including The Beatles. Hamburg is also known for several theatres and a variety of musical shows. St. Paulis Reeperbahn is among the best known European entertainment districts.