All Saints Day
November 1

All Saints Day was instituted to honor all the saints, known and unknown and, according to Pope Urban IV, to supply any deficiencies in the faithful's celebration of saints' feasts during the year. It originated with the fourth-century Eastern feast of All Martyrs that was celebrated on Easter Friday.  Pope Gregory IV established this commemoration of all the saints for the Roman Church in 835, celebrating on May 13.  In the ninth century, the feast day was moved to November 1 as a counter to the Celtic pagan feast of the Druids.

Día de los Muertos (Day of the Dead)
November 2

Next to Easter and Christmas, this is the most highly celebrated religious event in Mexico and elsewhere in Latin America. People usually visit and decorate graves between October 31 and November 2 around All Saints Day and All Soul's Day. Aid is asked of souls in heaven and prayers are said for souls in purgatory. The Day of the Dead festival combines Catholic traditions with local folk customs that started before the Spanish conquest to create a vibrant and unique celebration.