The Wandering Library

The Wandering Library is a tale told by many a bartender and innkeeper to adventurers around the world. Nobody knows when the story first began to spread around the world, and while many regions have their own variances on the story, the key points of the tale remain the same. The story is simple: Somewhere in the world, there was a vast repository of knowledge, an immense cache of catalogued information. This was not a fixed location, however, a dungeon that any half-baked adventurer could delve into and scour for its secrets. This place moved, under it's own power and by it's own will, all across the world. With no regard for the borders of nations or any attempts to stop it from its seemingly endless journey, this place became known as the Wandering Libaray.
The many variants of this tale paint very different pictures of the Wandering Library. Some say the Wandering Library is a massive spire that walks on mechanical legs, it's halls curated by constructs. Others say it's a floating fortress of knowledge, whose shelves are tended to by endless swarms of familiars. Others still say it's a normal building that simply teleports from place to place, at the whims of it's fae inhabitants. At this point, the truth of the Wandering Library, if it even exists, is lost to time.