The gold warehouse is the place to store the gold you receive through prizes and from your market place. You gain access to a gold warehouse when HQ reaches level 2. The higher the level of the warehouse the more gold can be stored at any given time. Gold is used for purchasing buildings, upgrades, healing, training and levelling up. There are a total of four gold warehouses to access during the game. To upgrade your warehouse, the HQ has to be at a certain level.