You know what every castle needs? A TREASURE ROOM!
Function: Anyone who has access to the dwelling can deposit gold and gems into the treasure room, but no withdraw.
Unique Display: Upon entering the castle, how much gold & gems the treasure room has will be displayed on the top of the page.
Important Note: All loot in the treasure room will be lost when the castle is sold, or no longer has an owner (character expired).
Not too sure if should be included ideas:
Plunder: If Treasure Room has gold in it, plunderers will steal from it instead of the coffers. Even if the Treasure Room has 1,000,000 gold, it will be treated as if it has 75,000 gold when plundered to avoid giving plunderers a ridiculous amount of gold. If gems is deposited, there is a very low chance that the plunder might manage to still one from plundering the castle's treasure room.