The tour of ‘Underground Naples’ is divided into three sections: 1) Graeco-Roman aqueduct. At a depth of approximately 40 m, visitors can explore the tuff chambers dug in the Greek period (4th century B.C.), used as cisterns for Naples’s water supply for about 23 centuries. The tour lasts about an hour; 2) tour of part of the city’s old Roman Theatre, which in the fifteenth century was incorporated into some houses still standing on Via Anticaglia, Vico Cinquesanti and Via S. Paolo; 3) summa cavea of the Roman Theatre. A permanent exhibition has been set up here, which uses some thirty antique wooden cabinets to house a collection of folk-art nativity and crib scenes.