Flood plaques
"Huc Tiber ascendit", the Tiber rose to this point: taking a walk through Rome's historical districts, it is easy to come across a large number of old plaques, made of marble or stone, that are embedded into the walls the churches, in the courtyards of the palaces and in the street corners. They tell us how high the waters of the Tiber reached in that particular area and they are memories of the battle that Rome has fought with its river. Throughout its history, Rome has experienced many floods, sometimes catastrophic. The problem was so big that, in 1875, Garibaldi proposed to deviate the Tiber from the city center but in the end the project by Raffaele Canevari prevailed and it was decided to build retaining walls, the so-called Muraglioni, which finally freed Rome from the constant threat of being flooded.
Resorting to old documents, etchings and other historical sources, it has been assessed that a total of 122 plaques were hung up to the 1930, most of them preserved. In the more elaborate ones, the waters are represented by wavy lines, while a stylized hand with a pointing finger indicates the actual level of the flooding on the wall. The oldest plaque is written in semi-Gothic characters and it was once hung on the facade of the church of Santi Celsio e Giuliano, close to Ponte Sant'Angelo. Today it can be seen under a small arch at one end of Arco dei Banchi, a side street of Via del Banco di Santo Spirito, and recalls the flood of November 1277. It is from this year that the floods are indicated with reliable and historically verifiable data.
A real hit parade of the most violent floods is still preserved on the facade of Santa Maria sopra Minerva, located in one of the lowest spots in Rome, which means that the water levels in this area could reach surprising heights: the oldest plaque dates back to 1422, followed by others dated 1495, 1530, 1598 and 1870. The first in the ranking was that of 24 December 1598, when the flow of the river reached 4,000 m3/s (the average flow of the Nile is about 3,000 m3/s) and the water was almost twenty meters high, a record that has not been surpassed. 11 plaques commemorate the event, including those on Via Santa Maria de' Calderari and on Lungotevere in Sassia. It was that flooding that damaged the ancient pons Aemilius, known at the time with the name of Ponte Senatorio, already renovated several times in the past and since then called Ponte Rotto.
During the flood of 28 December 1870, remembered by a number of plaques including under the portico of San Giorgio al Velabro, the water exceeded 17 meters: it was this latter circumstance that pushed the king Vittorio Emanuele to adopt decisive remedies. The most recent plaque is in the portico of San Bartolomeo all'Isola, decorated with a simple horizontal line and dating back to 1937: the new walls contained the current very well and the waters caused only modest flooding.