Dante called it “the cursed and unlucky ditch.” Half a millennium later, Tuscany’s Arno river would more than live up to that title. Just before dawn on November 4, 1966, the rain-swollen river abruptly broke its banks; its waters surged through Florence at speeds of 45 miles per hour and flooded the city with 18 billion gallons of mud and grime. Yet for all the destruction the natural disaster unleashed, it would also provide a major turning point for one of the city’s most beloved art-supply shops.

Among Tuscany’s more superstitious residents, l’alluvione (“the flood”) had been a long time coming. Since the Arno’s first recorded flood in 1177, Florence had already been swamped 55 times, with roughly one superflood for each century of its history. As historians would later note, both the earliest and most recent encounters with these superfloods—recorded in 1333 and 1844, respectively—had also arrived on November 4th.