Summary from Wikipedia

Relics of him were kept in the Church and Catacombs of San Valentino in Rome, which "remained an important pilgrim site throughout the Middle Ages until the relics of St. Valentine were transferred to the church of Santa Prassede during the pontificate of Nicholas IV".[6] His skull, crowned with flowers, is exhibited in the Basilica of Santa Maria in Cosmedin, Rome. Other relics of him are in Whitefriar Street Carmelite Church, Dublin, Ireland, a popular place of pilgrimage, especially on Saint Valentine's Day, for those seeking love.[7][8] At least two different Saint ...