The Herzog August Bibliothek is one of the most important research libraries in the world for medieval and early modern European manuscripts and printed books. Founded in 1572, it reached its zenith under Duke August the Younger, whose personal collection formed its core, and by the mid-seventeenth century it was the largest library in Europe with around 135,000 volumes. The building itself is a handsome baroque structure on Lessingplatz.
The library's greatest treasure is the Gospels of Henry the Lion, an illuminated manuscript made around 1188 for the Duke of Saxony and Bavaria. When it came up for auction in 1983 it sold for 32.5 million DM — then the highest price ever paid for a book. It is displayed in rotating stints alongside other manuscript highlights. Gottfried Wilhelm Leibniz served as librarian from 1691 to 1716, and Gotthold Ephraim Lessing from 1770 to 1781.
The library still functions as a major research institution and runs a programme of exhibitions, lectures, and academic events open to the public. The reading rooms are worth visiting for their atmosphere alone. Check the website for current exhibition schedules.