Kastelo Singa was a massive Panauan Army military base located in the Berawan Besar Mountains of Tanah Raya, Panau. During the Panauan Civil War, Pandak Panay interrogated captured CIA agent Jade Tan at the fortress, only for fellow agent Rico Rodriguez to rescue her. Panay's atomic submarine U1 destroyed the fortress with cruise missiles in a failed attempt to kill the escaping Americans.