Gothic II/The Castle

Talk to the people in the castle and enter what used to be the house of the ore barons. In the throne room (where Garond is) there is a chest that contains a map of the colony. You'll need the lockpicking skill to open it. Luckily, nobody cares about you taking stuff from chests. In the temple next door (where Milten is), you'll find a teleportation rune upstairs.