After the feast of Sts. Peter and Paul this is the greatest festival in the ancient Roman Liturgy. The terrible martyrdom endured by the famous archdeacon deeply impressed the generations that came immediately after him, for whom Lawrence became at Rome that which Stephen had been in Jerusalem.
In order to save from confiscation some property of the Church that had been entrusted to Lawrence, he sold it and gave the proceeds to the poor. As the enemies of the Church believed he had concealed the treasures and hope to make him reveal their hiding place, he was roasted alive on a gridiron. After an agony of hours he expired with a prayer on his lips for the conversion of the heathen.
His ashes were placed in peace by the priest Justin in the cemetery of Cyriacus. Constantine erected a basilica on the spot, which has since been rebuilt several times. The gridiron is still preserved in the old Church of San Lorenzo in Lucina.
(Source: The New Roman Missal, Rev. F. X. Lasance)