Ostia, Oratorio di San Quiriaco is a small late 4th century ruined shrine church just south-east of the theatre in the ruins of ancient Ostia.
The dedication was to St Quiriacus of Ostia
St Quiriacus (Quiriaco in Italian) is also known as Cyriacus or Cyriac (Ciriaco in Italian). The name comes from the Greek Kuriakos, "belonging to the Lord".
Unfortunately, the name was popular in early Christian times and this has led to serious confusion between several saints with the same name. Especially, beware of confusion with the Cyriac at San Ciriaco a Via Ostiense who was enshrined nearby up the road to Rome, and also with the one at San Ciriaco in the city itself.
The revised Roman Martyrology (2001) lists SS Quiriacus and Archelaus on 23 August as martyrs of an unknown date. The revisers rejected the story in the old Roman Martyrology as unhistorical. According to this, Quiriacus was bishop of Ostia who was martyred with Archelaus a deacon, Maximus a priest and several companions in the year 269 during the reign of Severus Alexander. However, there was no persecution of Christians in that emperor's reign.
The little church was the original shrine of St Quiriacus. It seems almost certain that an extant sarcophagus was re-used to hold his relics when they were enshrined here.
The church is on a complex site archeologically, and the ground level was raised substantially before it was built using re-used stone around the year 400. There is evidence of restoration using brick in subsequent centuries.
The shrine was recorded as still in use as a pilgrimage site in 1162, by which time it was probably the only intact building in the entire ancient town. However, it fell into ruin and was forgotten at an unknown date.
What survives of the church is part of a semi-circular apse, and a stub of wall to the east.Many confused remains of burials were found around the building and below the floor, and the most interesting of these is a sarcophagus with strigillate decoration and with a relief of the Good Shepherd, which had an epigraph on the lid Quiriacus dormit in pace ("Quiriacus sleeps in peace"). This is plausibly regarded as having been the saint's shrine. The sarcophagus has been left in situ, but the inscription is in store for safe keeping.