At end of each book there is a list of all the characters involved in the books, and their brief one-sentence descriptions. I think in the later books the list is like 20~30 pages.
There is an actual atlas of Westeros and The Known World, that was published back in 2012, The Lands of Ice and Fire.
The Wikipedia article about the world's geography is quite extensive and interesting too
I actually physically own this map ( as well as many others), and it's from the Lands of Ice and Fire map collection, which predates WOIAF by a year.
I don't own WOIAF, so I can't comment on that. Perhaps it reproduced the maps and made them canon.
You can buy this official map and support the artist that made it here: https://www.amazon.com/gp/product/0345538544/
It's from The Lands of Ice and Fire, $25 bucks on amazon.
His website is here: http://www.fantasticmaps.com/the-lands-of-ice-and-fire/