The Guardian: A recently discovered map of Middle-earth annotated by JRR Tolkien reveals The Lord of the Rings author’s observation that Hobbiton is on the same latitude as Oxford, and implies that the Italian city of Ravenna could be the inspiration behind the fictional city of Minas Tirith.
CityLab: The map could have easily been lost forever, having slipped out of an old edition of The Lord of the Rings belonging to the late famed illustrator Pauline Baynes. Baynes had been using the map to work on her own full-color poster edition of Middle-earth for Tolkien, who in turn, gave her precise and copious notes on the same document.
Also: See the Sketches J.R.R. Tolkien Used to Build Middle-Earth in the new The Art of The Lord of the Rings book.