Seville Catacombs

The Seville Catacombs (Osario de Sevilla) are a network of catacomb tunnels located below the district of Coria del Río, near Seville. They are believed to be the largest catacomb network on Earth, and were constructed during the late 14th Century. Their largest chamber, known as the Cámara Ósea, spans multiple kilometres of terrain and is notable for undergoing a catastrophic structural collapse during the 21st century, when archaeologists working for Industrial Occult Systems broke through the fragile chamber roof, weakening it and causing a chain reaction that resulted in structural failure of the supports.

This in turn caused the nearby ground to collapse into a sinkhole, threatening the integrity of the nearby Coria del Río Nuclear Power Plant, which was partially and unknowingly built on top of the Cámara Ósea. Ultimately, the plant was narrowly saved by the quick intervention of a Seville-based structural engineering firm. The IAEA later launched an enquiry into the foundational structural integrity of other power plants.