The Royal Library in Copenhagen (Det Kongelige Bibliotek) is the national library of Denmark and the largest library in the Nordic countries. It contains numerous historical treasures; all works that have been printed in Denmark since the 17th century are deposited there. Thanks to extensive donations in the past the library holds nearly all known Danish printed works back to the first Danish book, printed in 1482. The library was founded 1648 by King Frederik III who seeded it with a comprehensive collection of European works. It was opened to the public in 1793. In 1999, a new building adjacent to the old one was opened at Slotsholmen, known as the Black Diamond . The Black Diamond building was designed by Danish architects schmidt hammer lassen. Named for its outside cover of black marble and glass, it houses a concert hall in addition to the library.