From publisher blurb:
Centuries ago, the librarians of the Athenaeum of Tirinos saved thousands of precious tomes and scrolls from the book-burning legions of an invading army. Casting a powerful ritual, they whisked the entire library and its grounds away to safety on another plane of existence. Today, the Forgotten Athenaeum remains on the Astral Plane, collecting and preserving blasphemous texts, uncomfortable truths and dangerous lore. Using a hidden network of portals, visitors travel to the library from across the multiverse to browse its shelves and uncover its many secrets. This great wealth of knowledge attracts both innocent scholars and academics as well as unscrupulous spies and rogues. The next time your PCs need to track down an obscure piece of information, why not send them to the Forgotten Athenaeum?