From the martyrology:
"The holy martyrs Cyriacus, deacon, Largus, and Smaragdus, with twenty others who suffered on the 16th of March, during the persecution of Diocletian and Maximian. Their bodies were buried on the Salarian Way by the priest John, but were on this day translated by Pope St. Marcellus to the estate of Lucina, on the Ostian Way. Afterwards they were brought to the city and placed in the church of St. Mary in Via Lata."
Cyriacus was a Roman nobleman who converted to Christianity as an adult and, renouncing his material wealth, gave it away to the poor. He spent the rest of his life ministering to the slaves who worked in the Baths of Diocletian until he was tortured and put to death.