How Tolkien drew his world
Tolkien didn’t just describe Middle-earth: he drew it too, sometimes while working on the text. The Tolkien Estate website has sketches of Rivendell, different versions of individual scenes and finished illustrations for The Hobbit.
It’s particularly interesting to compare the preliminary drawings with the finished ones: in one view of Rivendell, the slopes draw closer together, the gorge deepens and the house becomes more sheltered. Changes like these reveal how the author refined his own idea of a place. Incidentally, The Hobbit wasn’t originally intended to be an illustrated book: the drawings were added after the publisher saw them.