- Siegen is a city located in the state of North Rhine-Westphalia in Germany. It is situated on the banks of the Sieg river and is known for its historic architecture, including the Upper and Lower Castles. The city has a population of around 100,000 inhabitants and is a major cultural and educational center in the region. Siegen is also home to the University of Siegen, which attracts students from all over the world. The city has a rich industrial history and was an important center for mining and metalworking in the past. Today, it boasts a vibrant cultural scene, with numerous museums, theaters, and festivals taking place throughout the year.