His birth date and birthplace are unknown. The feast of St. Valentine was first decreed in 496 by Pope Gelasius I, who included Valentine among those "... whose names are justly reverenced among men, but whose acts are known only to God." The creation of the feast for such dimly conceived figures may have been an attempt to supersede the pagan holiday of Lupercalia that was still being celebrated in fifth-century Rome, on February 15. As Gelasius implied, nothing is known about the lives of any of these martyrs. Many of the surviving legends surrounding them were invented in the late Middle Ages in France and England, when the feast day of February 14 became associated with romantic love.
According to the Catholic Encyclopedia, the saint whose feast was celebrated on the day now known as St. Valentine's Day was possibly one of three martyred men who lived in the late 3rd century during the reign of Emperor Claudius II (died 270)
It is believed that the priest and the bishop Valentinus are each buried along the Via Flaminia outside Rome, at different distances from the city. In the Middle Ages, two Roman churches were dedicated to Saint Valentinus: One was the tenth-century church Sancti Valentini de Balneo Miccine or de Piscina, which was rededicated by Pope Urban III in 1186. The other, on the Via Flaminia, was the ancient basilica S. Valentini extra Portam founded by Pope Julius I (337-352), though not under this dedication. In the catacombs connected with the basilica of Valentinus, outside the Porta del Popolo, nineteenth-century excavations unearthed two hundred Christian inscriptions. Lanciani reported, from the chronicle of the monastery of S. Michael ad Mosam, an account of a pilgrim of the eleventh century who obtained relics of saints "'from the keeper of a certain cemetery, in which lamps are always burning.'" He refers to the basilica of S. Valentine and the small hypogaeum attached to it (discovered in 1887)"