The Library
Knowledge: Places.
It will surprise no one that the library was the favourite hangout for many of the Zamorakian mages. They would read up on ancient mysteries, learn about new spells and they would work through the finer points of demonic contracts in a bid to avoid accidentally selling their souls.
There are rumours of a secret set of books detailing the sordid romances of the ancient Mahjarrat, but if anyone has found the hiding place of such grimoires, they have yet to share them with me.
Not that I care. I wouldn't read them. Honest.