Probably a ceremony of pagan origins, known as early as 1368, the Tree Weddings are officially celebrated here on may 8 every year since 1432, when Pope Eugene IV gave the forests of Mount Fogliano to Vetralla. The story intertwines since then with the tradition that requires, for the forest to remain in the property of the city, that the famous Tree Weddings be celebrated every year, when the mayor symbolically renews the city's engagement to the woods.

A procession of horsemen, ladies in traditional costumes, and flag-wavers then makes homage to the uncommon pair of spouses.