The Catacombs of Paris are an underground ossuary located in Paris, France. They hold the remains of over six million people, transferred from overcrowded cemeteries in the late 18th and early 19th centuries. The catacombs stretch for about 200 miles beneath the city, featuring tunnels and chambers lined with bones. Visitors can explore a small section of the catacombs, which is open to the public. The site is known for its eerie atmosphere and historical significance, reflecting the city's past struggles with burial space. The Catacombs serve as a reminder of mortality and the changing attitudes toward death in Paris.