A secret storage in a staircase can be a great hidden storage for bulky things that look unflattering when stored in full display. It’s the same space under stairs only hidden and accessed from the floor in the staircase. At: The Bottom Of The Stairs
Ice palace - The Kingdom of Tonophria in the north is beneath the ice. Accessible by tunnels and hidden passages going down, there is nothing but an expanse of ice reminicent of Antartica above. Possibly one of the most interesting Kingdoms in the saga.