Saw this link earlier, and some of these places looked simply amazing!
I have been to Paris numerous times, but it seems like I keep hearing about some amazing places that I have missed on each and every one of those prior visits! That would include these two bookshops in particular, although I fully intend to remedy that whenever I next get back to the City of Lights.
Some of these others, particularly the one in the Netherlands, as well as the one in Buenos Aires, look amazing, and worth a special trip, should I be so fortunate as to find myself visiting those cities someday!
In any case, here is the link to some of the most incredible bookstores in the world:
9 Awe-Inspiring Bookstores Around the World by The Book Insider, October 15, 2015: