This is one of the most influential travel books ever written. It was circulating in the mid-14th century, and by the year 1400 was "the most famous book in the world" and some version of it was available in every major European language. It was the only travel book in da Vinci's extensive library, and Columbus had a copy of it with him on board the Santa María. Shakespeare, Milton and Keats, among many others, knew it and referred to it.
The author was an English knight who travelled from 1322-1356 and served (or claims to have served) with both the Sultan of Egypt and the Great Khan. Indeed, he claims to have "been there, done that" about everywhere and everything in the fourteenth-century world.
How much, though, is fact, and how much simply travellers' tales and fantasy?
It has been suggested that "Mandeville's longest journey was to the public library", but this is unjust; a witty comment rather than realistic criticism. For a start, there were no public libraries. There were very few books at all, and most of those were theological works. Why is it that da Vinci - a great collector of books on every branch of human knowledge - possessed only this one travel book? To use sources was, of course, normal and expected - later travellers all borrowed freely from Mandeville - but there are many details in this work for which no known source can be cited. The fact seems to be that it started out as a pilgrim's guide to the journey to the Holy Land: this guide constitutes the whole first half of the book, and his comments and ideas on the Holy Land are very unexpected and of great interest. He insists that the Christians are not worthy to possess the Holy Land, and also that many non-Christians are good people. "We know not whom God loves or whom He hates." The thoughts not of a provincial hack pretending to have travelled but of one who has lived among the men and women he writes about.
And the rest of the book? Harder to judge. Judge for yourself when you read it. Either way, this is the authentic fourteenth-century world-view - and on that note, let me quote again from the Introduction: Mandeville's insistence that had he found company and shipping he too could have girdled the entire globe (and it is, incidentally, a modern slander that the medievals believed the earth to be flat) played, with his discussion of the Pole star, some part in the dissemination of important geographical concepts and in preparing for the great voyages of the next century on which our world-view is partly based.