What is the name for the underground passages and rooms used by the early christians?

The underground passages and rooms used by early Christians are called catacombs. These catacombs served as burial sites and places for worship, particularly during times of persecution when Christians sought refuge from authorities. They are often characterized by their intricate networks of tunnels and chambers, featuring tombs and religious symbols. Catacombs can be found in various locations, with some of the most famous located in Rome.