Roodmas (from Old English 'rood' rod, cross, and 'mas', mass) is an archaic English word meaning "Mass of the Cross". and also known as "Holy Cross Day" commemorates the finding by Saint Helena of the True Cross in Jerusalem on September 14th in the year 355. First begun to commemorate the dedication of the Basilica of the Resurrection, it was linked with the finding of the cross shortly thereafter and with the May 3rd celebration of the Catholic feast of the Invention of the Cross.
Roodmas is confused by some in the pagan community with the Celtic festival of Beltaine, which in the modern pagan calendar is celebrated usually on May 1st, due to the confusion between the May 3rd Catholic feast and the September Roodmas.