MARCO and MARCELLIANO, saints, martyrs. — They are commemorated in the Hieronymian Martyrology on 18 June. On the same date their Mass is found in the Gelasian and Gregorian Sacramentaries. The Itineraries of the seventh century mention them on the Via Ardeatina, lying beneath the altar of an above-ground basilica; the Salzburg Itinerary adds that they were twins and deacons.
An attempt has been made to identify their tomb, but none of the hypotheses advanced can be considered certain. The few details concerning their martyrdom are supplied by that romance, and hagiographical work, which is the Passio s. Sebastiani: it may therefore be said that nothing positive is known.
The Hieronymian Martyrology locates their tombs in the cemetery of Balbina on the Via Ardeatina, whereas the catalogue of the cemeteries places them in a cemetery of Basilio on the Via Ardeatina, which is entirely unknown.
In 1903 G. Wilpert believed that he could identify the cemetery discovered near the Trappist monastery then existing, now the Istituto S. Tarcisio, on the Via Appia, as the cemetery of Marco, Marcellino and Damaso mentioned in the Lib. Pont. for the works carried out by Pope Giovanni VII (705–707); but at that time the expression coemeterium meant a basilica; the two martyrs are identified as buried on the Via Ardeatina in the cemetery of Balbina, which has not yet been identified; the pilgrims of the seventh century visited their tomb in an above-ground basilica and not in an underground cubiculum, in which, instead, O. Marucchi wished to recognize the tomb of the «confessores sancti quos Graecia misit» whom Damaso includes in the group of s. Callisto.
The cemetery discovered in 1903 was already partly known to De Rossi; it consists of an above-ground area and an underground region which inscriptions, sarcophagi, and paintings assign to the fourth century.