The Klementinum Library

Located in Czech Republic, the building first opened in 1722 as part of the Jesuit university and people have marveled at the stunning baroque architecture ever since. Klementinum library is now considered the National Library of the Czech Republic. An artist named Jan Hiebl painted the intricate ceilings in building. Not only is it beautiful, but the library also holds more than 20,000 books. (Source)