Flip the script. Have a bunch of adventurers hired by a guild to take out a dungeon full of "monsters" goblins, ogres, etc. See how long it takes before they realize its a mall/bazaar or that the guild wanted it gone because the mall/bazaar owners refused to capitulate to the guild.
Little do they know that somewhere in that mall is a level 10 unarmed fighter, and somewhere else is a person with a gun in their belt. Those monsters are probably in trouble.