Crystal Catacombs

Underneath the palace, and possibly much of the city, lies Crystal Catacombs of Old Ba Sing Se, an ancient underground city deep within the earth. These catacombs are the remnants of the first settlement in the area, carved underground by earthbenders. As the old city spread to the surface, the caverns were abandoned but eventually reopened to the public by the tunnel Toph's Passage, leading to the catacombs from the Middle Ring. Inside the interior of the Crystal Catacombs still lie ancient stone structures, a waterfall and pool, and the luminescent green crystals that gave Ba Sing Se its fame.