Catacombs of Paris
The Catacombs of Paris or Catacombes de Paris are a famous underground ossuary in Paris, France. Located south of the former city gate, the "Barrière d'Enfer," the ossuary fills a renovated section of caverns and tunnels that are the remains of Paris' stone mines.
In 1786, the curate of the Archbishop of Paris consecrated the Paris catacombs as tombs. 
In 1897, forty-five members of the Paris orchestra met in the catacombs in full tuxedo to perform a concert. 
In 1920, Demona came to Paris and spent a considerable amount of time digging through the catacombs in search of the Praying Gargoyle. Her scheme was foiled by Fiona Canmore and Team Atlantis, and the Praying Gargoyle was destroyed. ("The Last")
Demona returned to Paris in 1980 to reclaim the reforged Praying Gargoyle, and after slaying Charles Canmore, she retreated into the catacombs while being pursued by Jason, Robyn, and Jon. Robyn was nearly killed by Demona, before being chased off by Jason. ("Estranged")
Real World Background
- Catacombs of Paris at Wikipedia, the Free Encyclopedia