Square in Florence with a white marker stone (circled in red) showing how high the Arno came. At this point the marker is more than 3 meters high.
1333 – Flood of the Arno River, causing massive damage in Florence as recorded by the Florentine chronicler Giovanni Villani.
1966 – Two-thirds of Florence, Italy is submerged as the Arno river floods; together with the contemporaneous flood of the Po River in northern Italy, this leads to 113 deaths, 30,000 made homeless, and the destruction of numerous Renaissance artworks and books.
November 3, 1966
- After a long period of steady rain, the Levane and La Penna dams in Valdarno began to emit more than 70,629 cubic feet (2,000.0 m3) of water per second toward Florence.
- At 2:30pm, the Civil Engineering Department reported "'an exceptional quantity of water.'"
- Cellars in the Santa Croce and San Frediano areas began to flood.
- Police received calls for assistance from villagers up the Arno valley.
- The flood's first victim, a 52 year old workman, died while trying to reach a crumbling aqueduct
November 4, 1966
- At 4:00am, engineers, fearing that the Valdarno dam would burst, discharged a mass of water that eventually reached the outskirts of Florence at a rate of 37 miles per hour.
- At 7:26am, the Lungarno delle Grazie cut off gas, electricity, and water supplies to affected areas.
- By 8:00am, army barracks were flooded.
- By 9:00am, hospital emergency generators (the only source of electrical power remaining) failed.
- Landslides obstructed roads leading to Florence, while narrow streets within city limits funneled floodwaters, increasing their height and velocity.
- By 9:45am, the Piazza del Duomo was flooded.
- The powerful waters ruptured central heating oil tanks, and the oil mixed with the water and mud, causing greater damage.
- Florence was divided in two, and officials were unable to immediately reach citizens of the city past the Piazza Michelangelo.
- At its highest, the water reached over 22 feet (6.7 m) in the Santa Croce area.
- By 8:00pm, the water began to lower.
The flood has had a lasting impact on Florence, economically and culturally. City officials and citizens were extremely unprepared for the storm and the widespread devastation that it caused. There were virtually no emergency measures in place, at least partially due to the fact that Florence is located in an area where the frequency of flooding is relatively low. In fact, approximately 90% of the city's population were completely unaware of the imminent disaster that would befall them as they were sleeping during the early hours of November 4, 1966.
Residents were set to celebrate their country's World War I victory over the Austrians on November 4, Armed Forces Day. In commemoration, businesses were closed and many of their employees were out of town for the public holiday. While many lives were likely spared as a result, the locked buildings greatly inhibited the salvaging of valuable materials from numerous institutions and shops, with the exception of a number of jewelry stores whose owners were warned by their night watchmen.
Tragically, 5,000 families were left homeless by the storm, and 6,000 stores were forced out of business. Approximately 600,000 tons of mud, rubble, and sewage severely damaged or destroyed numerous collections of the written work and fine art for which Florence is famous. In fact, it is estimated that between 3 and 4 million books/manuscripts were damaged, as well as 14,000 movable works of art.
Artist Marco Sassone, in an 1969 interview, recalled the impact of the flood on Florence's residents, "The only thing you could do was watch and be helpless. Nature was master...the women became crazy with fear. They began throwing things from the windows and screaming 'who is going to save my children?'" It was reported that 101 people lost their lives in the flood waters
- Archives of the Opera del Duomo (Archivio di Opera del Duomo): 6,000 volumes/documents and 55 illuminated manuscripts were damaged.
- Gabinetto Vieusseux Library (Biblioteca del Gabinetto Vieusseux): All 250,000 volumes were damaged, namely titles of romantic literature and Risorgimento history; submerged in water, they became swollen and distorted. Pages, separated from their text blocks, were found pressed upon the walls and ceiling of the building.
- National Library Centers of Florence (Biblioteca Nazionale Centrale Firenze): Located alongside the Arno River, the National Library was cut off from the rest of the city by the flood. 1,300,000 items (or one-third of their holdings) were damaged, including prints, maps, posters, newspapers, and a majority of works in the Palatine and Magliabechi collections.
- The State Archives (Archivio di Stato): Roughly 40% of the collection was damaged, including property and financial records; birth, marriage, and death records; judicial and administrative documents; and police records, among others.