The Clementium Library (spelled "Klementium" in Cezch) in the beautiful city of Prague is widely held to be among the world's most gorgeous libraries. It was opened in 1722 and holds over 20,000 books. The magnificent ceiling frescoes were painted by artist Jan Hebl, and the library was originally part of a Jesuit college. In 1990, it was designated as the national library of the Czech Republic.
Covering a total of over 20,000 square meters (approx. 2.15 million square feet), the library is the second largest complex of buildings in Prague, second only to the Prague Castle. It was once the third largest Jesuit college in the world. Starting in 1775, local weather patterns were recorded and kept in the library, a process which continues to this very day. The Clementium was also mentioned in Jorge Luis Borges' "The Secret Miracle" during a character's dream sequence.
Via: Bored Panda