The modern St. Valentine's Day celebrations are said to have been derived from both ancient Christian and Roman tradition. As per one legend, the holiday has originated from the ancient Roman festival of Lupercalis/Lupercalia, a fertility celebration that used to observed annually on February 15. But the rise of Christianity in Europe saw many pagan holidays being renamed for and dedicated to the early Christian martyrs. Lupercalia was no exception. In 496 AD, Pope Gelasius turned Lupercalia into a Christian feast day and set its observance a day earlier, on February 14.