Abstract from Wikipedia -
Funny, isnt it? If so little is actually known about the group of saints who gave their life for the masses, still this day is celebrated on such a vast scale.
Saint Valentine (in Latin, Valentinus) is the name of several martyred saints of ancient Rome. Of the Saint Valentine whose feast is on February 14, nothing is known except his name and that he was buried at the Via Flaminia north of Rome on February 14. It is even uncertain whether the feast of that day celebrates only one saint or two or more saints of the same name. For this reason this liturgical commemoration was not kept in the Roman Catholic calendar of saints for universal liturgical veneration as revised in 1969. Traditional Roman Catholics continue to venerate St. Valentine on his feast day, February 14.