According to an ancient tradition, on the 5th of August in the year 358, snow covered the Esquiline Hill. The event was foretold in a vision Pope Liberius had of the Virgin Mary, who told him to build a basilica at that place the snow appeared. That marked the origins of the Basilica of Saint Mary Major.
Since that time, every August 5th, the Basilica hosts the celebration of the miracle of the snows.
During the Gloria at the celebration of Mass, a cascade of white flower petals fall in memory of that day when the Esquiline Hill was found to be snow covered, despite the August heat of Rome.
The celebrates marks one of the more unique celebrations in the Eternal City.