Instituted to honour all the saints, known and unknown. It owes its origin in the Western Church to the dedication of the Roman Pantheon in honuor of the Blessed Virgin Mary and all the martyrs by Pope Saint Boniface IV in 609, the anniversary of which was celebrated at Rome on 13 May. Pope Saint Gregory III consecrated a chapel in the Vatican basilica in honor of All Saints, designating 1 November as their feast. Pope Gregory IV extended its observance to the whole Church. It has a vigil and octave, and is a holy day of obligation; the eve is popularly celebrated as Hallowe’en.