Orebro is a beautiful town located in the very heart of Sweden. Its old town, Wadkoping, located on the banks of the River Svartan, contains many 18th and 19th century wooden houses, museums, and exhibitions. The great water tower of Orebro, nicknamed The Mushroom, is an excellent viewing point. Another landmark is the medieval fortress located on an island in the River Svartan, which was transformed into a major castle in the 16th century. Orebro also offers a variety of sporting and leisure activities in town, in the mountains and by Lake Hjalmaren, the fourth largest lake in Sweden. The marshes around the outlet of the Svartan into Lake Hjalmaren are a famous bird watching area.