See the Sketches J.R.R. Tolkien Used to Build Middle-Earth

Tolkien wrote The Lord of the Rings but he also drew it:

The many maps and sketches he made while drafting The Lord of the Rings informed his storytelling, allowing him to test narrative ideas and illustrate scenes he needed to capture in words. For Tolkien, the art of writing and the art of drawing were inextricably intertwined.

In the book The Art of The Lord of the Rings, we see how, and why.

My sneak peek of his sketches for Wired.com