When we started in Essen we visited a lot of different places and sights. We also visited the Gasometer in Oberhausen. It is one of those rare places I really like. The atmosphere is pretty cold. I always suggest stepping outside on the top and seeing the landscape of the Ruhr-Area. I'm not sure but I think that you are able to walk the stairs to the top instead of taking the elevator. From time to time they change the exhibition. During my 8 years in the Ruhr-Area I never saw a bad exhibition, expect those made by Christo.
Canon EOS 40D