What makes visiting the Basilica of Saints John and Paul fascinating is visiting the ancient Roman Houses (Case Romane) upon which the church was built. You have the opportunity to explore a magnificent underground complex that once was an "insula" (apartment building) and various Roman houses dating from 2nd to 4th century AD. They were later transformed into an opulent Roman residence with about 20 rooms finely decorated with frescoes, mosaics, and various architectural details. Not to be missed are the Room of the Geni (“geniuses” are ancient Roman mythological guardian spirits), Room of the Imitation Marble, the Room of Orant (“worshipper”), the Confession, the Baths, the Nymphaeum of Proserpina, and the Antiquarium - the Greek cross-shaped museum that houses Roman object excavated beneath the basilica that offers visitors a glimpse into the everyday life of ancient Romans and the objects they used in their homes.Entrance fee € 6 per person, € 4 per person for students and seniors, Free for children under 12. CLOSED on Tuesdays and Wednesdays. On these dates, you are invited to visit the equally fascinating San Clemente Basilica with visits to the Underground ancient 4th-century basilica and 1st-century pagan temple. Entrance fee € 10 per person to be paid on site.