On August 5, the Church celebrates the Dedication of the Basilica of St. Mary Major, commemorating the Miracle of Our Lady of the Snows. According to ancient tradition, the Blessed Virgin Mary appeared in a dream to the Roman nobleman John and to Pope Liberius, asking that a church be built in her honor where snow would fall. Though it was the height of summer, fresh snow covered the summit of Rome's Esquiline Hill on August 5. The Pope is said to have traced the outline of the future church in the snow, and a basilica was erected on the site.

The present Basilica of St. Mary Major, rebuilt under Pope Sixtus III after the Council of Ephesus proclaimed Mary as Mother of God in 431, remains one of the most important Marian shrines in the world. Each year on August 5, white flower petals fall from the basilica's ceiling, recalling the miraculous snowfall and honoring Our Lady's maternal care for the faithful.