Presumably its canonical location is still in a cave beneath the Wilderness, where Saradomin had kept it hidden.Bizarre Boron Fusswell, scryer extraordinaire. Minigames & ninja fixes & achievement ideas!
Perhaps you're half right; perhaps we can't win. But we can fight.
There's no reason to believe it's anywhere other than under the wilderness. If you want to see the portal leading to it as canonlore then you might want a headcanon that some wizardtypes were really sick of having to go out in the wilds and they made a faster way... and then with disuse the opening leading to the cave collapsed and no one's really bothered to reopen itCarn