I stumbled upon this gem of a bookstore (in searching online, not in real life, alas):
Behold! El Ateneo Grand Splendid!
This grand hall in Buenos Aires, Argentina started as a performance area for all kinds of events, like dancing and music. In the 1920s it was turned into a cinema, with seating installed. Then in 2000, a company leased the building, removed the seating, and turned it into a flagship bookstore for their publishing house. Pretty impressive history of artistic involvement in this building!