Catapult Cave

Here's "catapult cave", my brilliant name for this huge cave filled with rotted catapults, just north of the huge iron door:

There may be treasure within--the place is so huge and so dark, who can tell?--but it's swarming with zombies.  Far too many to fight.  The PCs will have to use magic (perhaps find a protection scroll) or stealth (risky though) to explore it.