The where?
Just kidding.
But you’re a rare one to think about the Old Sanctuary. Not much is remembered of it at all. Floating Tudor houses tied down with ropes… underground caverns filled with serpents and circuses… an ivory tower, and a magical mafia? No such things ever were there. Perhaps you're confusing it with the new Sanctuary?
The City remains, but it has become the picture of dullness. Nothing survives of The Sun, that grand gilded palace, or the Grand Library. There are no longer whispers among the alleyways of crowded cities of a refuge for those exiled from society. It is simply a place, now.
The Old Sanctuary is no more than a ruin now: and not much of it is remembered at all. Your nostalgia is understandable, but you are quite alone in it.