The Paris Catacombs are a vast network of underground tunnels and ossuaries located beneath the city of Paris, France. Originally limestone quarries, they were transformed in the late 18th century to house the remains of over six million people, as cemeteries became overcrowded. The catacombs stretch for approximately 200 miles, with only a small section open to the public. Visitors can explore the catacombs through a designated route that showcases the eerie yet fascinating arrangement of bones and skulls. The site serves as a reminder of Paris's history and the challenges of urban burial practices, attracting tourists and history enthusiasts alike.