Not sure when or how it should become active, I'm throwing it out there as a suggestion.
the idea being that it is heavily fortified and gold, elixir or dark elixir could be stored in it, at each level the space increases but each player can decide what they put in there. Eg if the space was 100 a player could put 50 g, 30 e and 20 d. When a player deposits the goblins take a 5% protection fee.
the building can get destroyed in raids but no resources are taken as the goblins have the loot hidden deep underground and protected by enchantments.
