All Hallows' Eve, October 31
All Hallows' Eve is the day prior to Samhain and All Saints' Day. Origins of the festival can be traced back to Scottish Celts who celebrated the end of harvest festival Samhain.
It is during this time that the Celts thought that spirits came back on Earth to mix with the living.
The Celts would wear masks and light bonfires to honour the dead and keep them away from the living.
The Romans later brought their own traditions such as apple bobbing and cider drinking.
In 835, Pope Gregory changed the "All Saints Day" celebration from May 13 to November 1, to coincide with Samhain.
October 31 was therefore celebrated as a "holy evening" which is how the term "All Hallows' Eve" emerged.
Nowadays, All Hallow's Eve is better known as Halloween, and the association with ghosts and spirits has continued.
Halloween Jack-O'-Lanterns, by Kathryn Stevens