Up Helly Aa refers to winter fire festivals held in Shetland, Scotland annually in mid-winter marking the end of the yule season. The Lerwick celebration involves up to 1000 costumed participants marching in squads through town, growing out of older traditions of dragging burning tar barrels. Over time, the celebrations became more elaborate, with Viking themes being introduced in the late 1800s including burning a longship replica. While originally a young working class male event, Up Helly Aa is now larger and more organized while maintaining connections to its origins over 150 years ago.