1. Naples Underground, also known as Napoli Sotterranea, is a fascinating network of tunnels, caves, and cisterns located beneath the historic center of Naples. These underground spaces date back to ancient times and have been used for various purposes throughout history, including as ancient Greek and Roman aqueducts, as tuff quarries, and as shelters during World War II. Visitors can explore a small portion of this underground world on guided tours, which offer a glimpse into the city's rich history and provide a unique perspective on Naples.

2. Naples Underground is open to visitors during specific guided tours, which typically run several times a day. It is recommended to check the official website or contact the site directly for the most up-to-date information on tour times and availability. Unfortunately, a phone number is not available at the moment.

3. Ticket information and transportation: Tickets for guided tours of Naples Underground can be purchased at the site or online in advance. Prices vary depending on the type of tour and any discounts available. To reach Naples Underground, visitors can take public transportation to the historic center of Naples and then walk to the site. Alternatively, taxis or rideshare services are also available for transportation to the site.