Trinity College Library

Location: DublinOpened: 1592 Number of books: 6mThe largest library in Ireland serving both Trinity College and the University of Dublin, this ornate space is the home of the gospel manuscript the Book of Kells, two volumes of which are on permanent display.

Kremsmünster Abbey Library

Location: AustriaOpened: 1689Number of books: 160,000This private library is the oldest and largest of its kind in Austria and was built by Baroque architect Carlo Antonio Carlone. Four rooms are accessible to the public: the hall of the Greeks, the hall of the Latins, the Small Department and the Benedictine Room. Each room is named after the frescos created by painter Melchior Steidl, who honoured famous historians, scholars and literary figures with his rainbow creations. Among them are Plato, Aristotle and the Queen of Sheba. The most valuable book is the Codex Millenarius, a Gospel volume written in around 800 AD at Mondsee Abbey.

The National Palace of Mafra

Location: Portugal Opened: 1771Number of books: 36,000Home to more than just books, this striking space houses a permanent colony of miniature bats, which swoop in at night to eat the bugs that would otherwise damage the library’s collection of books. In addition to its innovative pest control team, the room’s 18th-century Rococo architecture makes it the most exquisite space in the palace.

The Vatican Apostolic Library

Location: Vatican CityOpened: 1475Number of books: 1.1mCommonly known as the Vatican Library or more simply as the Vat, this colourful gallery is the official library of the Holy See and is used for research purposes. Open to anyone who can prove their qualifications and research needs, the space houses texts on history, law, philosophy, science and theology, as well as 75,000 codices (ancient manuscripts) and some 8,500 incunabula (books printed before 1501).