The complex, described in the sources as “inter duas lauros” from the ancient name of the place, includes the Catacomb of Marcellinus and Peter, the basilica of the same name and the Mausoleum of Helena, also known as Tor Pignattara. The access to the catacombs is from the courtyard of the basilica. The tombs of the two saints (with whom pilgrims were wont to worship Tiburtius, Gorgonius, the Four Crowned Martyrs and two groups of anonymous martyrs, all victims of Diocletian persecution) were at first two simple burial niches, then enriched by monumental marble decorations as wished by Pope Damasus (366-84), who seemed to have known the vicissitudes of Marcellinus and Peter from their own torturer. Damasus made the access stairs and an obligatory path for pilgrims, which wound above and underground. The bodies of the two martyrs remained in the underground crypt until the papacy of Gregory IV (826), when they were brought to France and then to Germany. The great worship of the faithful is proved by numerous graffiti in the little apse and in the galleries that lead towards the tombs of the martyrs. Not only there are invocations in Latin, but also in Runic as a proof of the fact that the place for worship was attended by the Celts and the Germans. The catacombs, decorated by biblical scenes, are among the biggest of those present in Rome. Honorius I (625-38) built a little underground basilica with an apse to receive the more and more numerous faithful, he doubled the access stairs to the basilica and consecrated an altar above the two niches. The new sanctuary dedicated to the Four Crowned was created between the V and VII centuries and connected to the first martyrial core with one-way paths marked with skylights. Moreover, to help the walk of the crowd of pilgrims, the secondary galleries and niches were blocked and new staircases were built. Eventually, Adrian I (last quarter of the VIII century) did the last extension of the building. Among the paintings is worth seeing the Epiphany and the two Magi.