All Saints Day, a festival in honor of all the angels and saints of heaven, observed in the Roman Catholic church on Nov. 1, and also in the Protestant Episcopal and Lutheran churches. In the eastern churches the same festival has been observed since the 4th century. In the West, it was instituted by Pope Boniface IV. in the early part of the 7th century, on the occasion of dedicating the Pantheon, a temple built by Marcus Agrippa, 25 B. C, in honor of Jupiter the Avenger and all the gods, to the worship of the true God, under the invocation of the Virgin Mary and all the saints. The feast became general in the 9th century. It is also called All Hallows.