Altena Burg, or castle, is a huge structure built from the 12th to 16th centuries. It is one of the largest medieval castles in Germany. It has three gateways, a central keep and a bailey. The castle, which overlooks the town of Altena, was built for the Counts of Mark, and has since passed through many owners and roles during its lifetime; however in 1912 it became the world’s first youth hostel, furnished with 300 beds in dormitories. This is now one of a number of museums inside the castle. The others are the museum of wire production (Drahtmuseum), and the history of the Mark district. Many of the old halls and rooms can be visited.