I broke my nail, like really badly, while I was here. I still remember how much it hurt, even though it was five months ago. But I can't fault Caliban because I broke my nail for the very best reason: the books were packed so tightly on the shelf that I somehow cracked it trying to pull out a desired title. See? Awesome!
When I go to bookstores I check out the photo/art books, and now history and Western US history sections. Caliban had a really nice selection of titles -- not just the picked over bargain book stuff, but a good mix of recent and older/classic titles, all in great condition and at competitive prices. It's definitely worth the visit.
I found them on my third trip to PGH, and only wish I found it sooner.