This is one of Antwerps best kept secrets, because it only recently opened up to the public. Think of magical Harry Potter vibes... The library is called the Hendrik Conscience heritage library, and the special rooms name is the Nottebohm room. This room houses the first 150.000 books of the library, which in total consists of 36 kilometers of books!
This room used to be a chapel, and is normally only open for lectures, exhibitions, concerts or for recordings of movie scenes. Since 2023, it opens up in summer for the public. So make sure to visit between the 15th of June and the 15th of September, and specifically during August if you want to see the rare Antwerp book of songs dating back to the 16th century. You can even listen to the modern translation of the book.
You can buy tickets online or at the reception of the library, for only €8 for an adult. Visit every afternoon between Tuesday and Sunday to experience this hidden part of Antwerps history.