The Crystal Catacombs are huge chambers made of rock and crystal located deep beneath Far Drop's Cabbage Farms. The Crystal Catacombs are a part of Old Far Drop. After the development of Far Drop as a large metropolis, it was a small underground settlement carved out of the rocks by earthbenders. As the Sky Pirates excavated further, they discovered the Green Eco Crystals and began to mine them; these glowing crystals are now used as a common light source in Far Drop. Eventually, the city expanded above ground, leaving the Crystal Catacombs empty. Although no one lives there today, the ancient underground city of stone still stands.
The part of the ancient city that was used as a bomb shelter appeared to be nothing more than a large cave where old stalagmites and stalactites had joined to form large, strong pillars designed to support the weight of the roof. Many Green Eco Crystals were embedded in the walls, providing light for it's occupants.
The old city was composed primarily out of rock houses; some of them were merely excavated out of the wall while others were built against the wall. All of the houses that remained in the old city appeared to be very crude in design: one large hole served as an entrance and one or more smaller holes functioned as windows. There was no sign of other decoration. Many stairs led up from the paved floor to the numerous houses that were built into the wall.
A river ran through the center of the large cave that served as the city's main plaza. The ancient earthbenders had used their bending to shape the riverbed into neat channels in order to provide water to all corners of the large cave. The water itself made its way into the underground cave through a waterfall at one end.
Large stone columns stood at regular intervals to support the heavy roof and prevent it from caving in. The light of the city was provided by the naturally luminescent crystals that were spread all over the walls and floor.