Hamburg is a major port city in northern Germany and third largest port in Europe. It is connected to the North Sea by the Elbe River. The city's metroplotan region is home to more than five million people. Hamburg has a history as a member of the medieval Hanseatic League and a free imperial city of the Holy Roman Empire. Hamburg is a major European science, research, and education hub, with several universities and institutions. Among its most notable cultural venues are the Elbphilharmonie and Laeiszhalle concert halls.