Copenhagen is Denmark's capital and most populous city, and its first economic, political and cultural center. The city is inhabited by about half a million people. It is a very ancient city dating back hundreds of years. It was founded by the Vikings in the tenth century as a village for fishermen, and it became the capital of Denmark in the fifteenth century. This city extends on two adjacent islands, and bridges link the two parts of the city. This city is characterized by its many beautiful buildings and historical monuments that still exist today. Among the most prominent of these are Kristenberg Castle, where the Danish Parliament is now located, Princen Palace, which currently houses a National Museum, the Royal Palace dating back to the eighteenth century, and the Royal Library, which It contains more than 600,000 volumes. Copenhagen is an important industrial center, and its industrial products include diesel engines, furniture, Chinese porcelain, sports machines, and many others.