This hushed building one of the world’s best reference libraries for 17th-century books (if you’re a member, that is). Its collection of 800,000 volumes also includes what’s billed as the ‘world’s most expensive book’ (€17.5 million at the time of purchase in the 1980s): the Welfen Evangelial, a gospel book once owned by Heinrich der Löwe. The original is only on show sporadically, but an impressive facsimile is permanently displayed in the vault on the first floor.
