The history of Naples Underground spans over 2,000 years, beginning in the 4th century BC when the ancient Greeks quarried tuff stone from beneath the city to construct Neapolis, their new settlement. These initial excavations laid the groundwork for the extensive network. Under Roman rule, the underground system was significantly expanded. The Romans engineered an elaborate aqueduct system, utilizing the existing Greek tunnels and excavating new ones, to channel water from the Serino springs to every part of the city. This engineering marvel served Naples for centuries. Over time, as new aqueducts were built, sections of the ancient system fell into disuse. During World War II, these forgotten passages found a new purpose, serving as vital air-raid shelters for thousands of Neapolitans seeking refuge from Allied bombings. Evidence of this period, including personal belongings and graffiti, remains visible today. After the war, the tunnels were largely abandoned again until dedicated efforts began in the late 20th century to clean, restore, and open them to the public, transforming them into a captivating historical attraction.