If you go to a dreary part of the city and make your way down some drearier stairs you can make your way into Obriss Books. The finest book shop there is.

In the first chamber, Mistress Obriss keeps a watchful eye on the rarest tomes, though the magical protection also does a surprising amount of the work. To the left are her private chambers but remember that very few get to see them. The door to the right leads to the rest of the shop, hundreds of tomes and curios for the interested adventurer.

I wanted/needed an underground bookshop so I made one. Probably work well for something like a wizards archive or similar.