Alberto Manguel and Gianni Guadalupi:
The Dictionary of Imaginary Places
Macmillan 1980 (1987, 1999)
I fell upon this book when it was first published like a punter attacking an ice-cream during the interval in an over-hot theatre. Just the title had me drooling, and once inside the book I was in seventh heaven. First of all it took places described in a range of literary works as literally true by giving each a Baedeker-style travel guide entry. Then, like any good Baedeker it provided maps and charts giving visual aids to familiar and unfamiliar locations. There have been at least two revised editions since 1980 but this was the first attempt to give an overview of dystopias, utopias, fantasy worlds and comic geographies from different cultures, languages and centuries. The mock-seriousness is sometimes leavened with equally tongue-in-cheek humour though I found that at times the terseness of some entries could be wearing.
Just a few examples of entries, almost at random, may give you a flavour.