The ancient Romans referred to this day as Dies Natalis Invicte Solis, the Birthday of the Unconquered Sun. The Roman Saturnalia festival occurred at this time, during which riotous merrymaking took place: schools were closed, the army rested, no executions were conducted, masters and slaves feasted at the same table, and people donned costumes and danced through the streets. Many European celebrations have involved holly and mistletoe (which ward off evil spirits), evergreen trees (a reminder that the growing season is coming soon), and ceremonial fires (lit to incite the return of sunlight and honor the rebirth of the Sun God). The highlight of the festivals, the Yule log, traditionally burns throughout the longest night of the year, then smolders for 12 days before it is ceremonially extinguished.