Oberhausen, with its population of 223,000 one of the middle sized cities in the Ruhrgebiet, has probably undergone the most radical changes not only in economic structure but also in the general character of the city. The "Neue Mitte Complex" with the CentrO. is the driving force behind the structural change and booming municipal tourism. Every year 23 million visitors come to this attractive shopping and leisure complex with one of Germany`s most modern multi-purpose halls, the Oberhausen Arena. Around CentrO., built on the site of a former steel works, further tourist attractions are being planned or are in the pipeline. The 117 metre high gasometer was reconverted into what is probably the world`s most original exhibition centre. So far the five exibitions already staged here have attracted 1.7 million visitors into this industrial giant. Adjacent to the gasometer, on the Rhine-Herne-Canal, a large sea-water aquarium will be developed, based on the "Oceanario" in Lisbon. Oberhausen`s World of the Future Theme Park, O.vision, is in the planning stage, featuring a 140 metre long and 47 metre high transparent Glass giant which allows the visitor to make a veritable journey of discovery through the human body.