Founded in 1873, the factory was taken over in 1881 by the Röchling family and went on to become a major industrial centre, carrying out all the stages in the production of cast iron and steel. For a century, this factory was the life and soul of the town, employing over 16 000 people. Now open to the public, it has been a UNESCO World Heritage Site since 1994. The highlight of the visit is the huge workshop of gas-blowing engines.