Most expensive book (adjusted for inflation)

Originally sold for $30,802,500 (£19,246,489) at Christie's, New York, USA on 11 November 1994, or $49.4 million if adjusted for inflation as of 2014, the Leicester Codex, a collection of written observations, musings, theories and illustrations by the Italian Renaissance artist Leonardo da Vinci, is the most expensive book ever sold – according to Forbes. Purchased by Microsoft co-founder Bill Gates (USA), the Codex is a hand-drawn and written notebook created over several years by da Vinci, who began the work on the precious volume sometime around 1508. The pages of the Leicester Codex are approximately 30 cm x 22 cm in size. Although the sheets are currently displayed separately, they were once bound together in the form of a book.

Forbes' full top 10 - adjusted for inflation - ran as follows:

1. Codex Leicester ($49.4 million, 1994)

2. The Gospels of Henry the Lion Order of St Benedict ($28 million, 1983)

3. Magna Carta ($24.5 million, 2007)

4. St Cuthbert Gospel ($15.1 million, 2011)

5. Bay Psalm Book ($14.5 million, 2013)

6. The Rothschild Prayerbook ($13.9 million, 2014)

7. Birds of America John James Audubon ($12.6 million, 2010)

8. The Canterbury Tales Geoffrey Chaucer ($11.1 million, 1998)

9. Copy of the Constitution, Bill of Rights and other key acts of the first Congress in 1789, George Washington ($10.2 million, 2012)

10. Comedies, Histories, & Tragedies (1623), The First Folio William Shakespeare ($8.2 million, 2001)