Up Helly Aa (/ˈʌpˌhɛliə/ up-hel-ee-ə; literally "Up Holy [Day] All") refers to any of a variety of fire festivals held in Shetland, in Scotland, annually in the middle of winter to mark the end of the yule season. The festival involves a procession of up to a thousand guizers in Lerwick and considerably lower numbers in the more rural festivals, formed into squads who march through the town or village in a variety of themed costumes.