The Royal Library, on the island of Slotsholmen, is made up of two sections: the original building, founded in 1648, and the modern extension, completed in 1999. The newer part of the library sits gleaming on the shores of Copenhagen harbor; it’s known as the Black Diamond due to its shiny marble exterior.
The library holds almost every book ever printed in the Danish language, with some titles dating back as far as 1482. The interior is a fascinating piece of architecture and the central hall is accessible to the public, but books must be reserved in advance and accessed in one of the reading rooms.
Planning tip: Between the charming historic side of the library and the entrance to the Danish Parliament you’ll find a peaceful hidden garden where you can sit by the fountain and take a break from a busy day of exploring.