LOCATION: Head across the bridge from Moonbrooke, then south through the forest and continue south until you're just north of the foothills to the south. Now head directly west. You'll walk directly left for quite awhile, but soon you should see some brush-covered plains, and mountains below. Head south between those mountains and you should see Moonbrook Castle, situated at the center of a swampland.
This is one stop that is completely optional. However, the enemies in this area are great for leveling up any weak characters. You'll mostly find zombies throughout, and they may hit hard but at least they leave behind good experience points and gold.
Also, you may sometimes run across a metal slime enemy. These guys are strong against magic, and they typically flee the moment they've been hurt. However, winning a battle against one will cause you to receive 135 experience points and 78 pieces of gold.
As far as the treasure chests go, well, they contain absolutely nothing. About the only other thing to do here is to talk to the spirit that rests in a ruined prison cell to the left (it will reveal the location of the Mirror of Ra), or to talk to the spirit of the King to the upper right for a nice little pun. Have fun poking around, or skip this location entirely. It's your choice.