One of the most favorite places in Istanbul since my trip here in 2015 - I went to the sound of music - Juma has a great taste for both it (a constantly replenished selection of vinyl) and books.
In addition to a wide selection of literature on art and music in different languages, there are many books on philosophy, politics, and sociology on the shelves.
If you have not yet managed to fall in love with the city while walking along the streets of the old city or its European part, you can fix it with a cup of tea with a book about Istanbul. Here you can always find photo albums, books about architecture, fiction (Pamuka, of course)