Located along the river Ruhr, Essen was traditionally a significant coal and steel center, one of the largest in Germany. Essen has modernized, hosting a number of large German corporations and boasting a vibrant cultural offering at a number of venues, particularly the Aalto Theater, which is an architectural masterpiece and home to ballet and opera. Essen is also regarded to be a “city of shopping”, particularly since the opening of the Metropolis shopping mall.