It may not be the most famous leaning tower in Italy, but the Garisenda Tower has now caught the attention of the entire country as scientists find it is in danger of collapse.
Scientists at the University of Bologna used highly sensitive microphones to pick up every crack in the tower.
Now the streets around Bologna’s 900-year-old tower have been closed after sensors detected unusual changes in the stonework.
At 157 feet tall, the Garisenda Tower has a four-degree slope—just less than the five-degree slope of the famous Leaning Tower of Pisa.
Experts believe the tower’s weak foundations could give way and an injection of fill material may be needed to provide greater stability.
The area around the Garisenda Tower was closed to traffic after unusual vibrations and noises were detected coming from the masonry
Bologna’s Garisenda Tower is dwarfed by its neighbor, the Asinelli Tower, and doesn’t quite reach the dramatic angle of the more famous Leaning Tower of Pisa
A representative of Bologna’s tourist board said that scientists detected unusual noises, oscillations, vibrations and movements of a few millimeters in the tower.
They add that the traffic restrictions will allow tracking devices to make more accurate recordings before sending specialists to climb the tower to take more precise measurements.
“Given the cultural importance of the Garisenda Tower, its hypothetical loss would be tragic not only for tourism, but also for the history of Bologna and Italy,” the spokesman said.
“Fortunately, the signals recorded so far do not allow us to conclude that the tower may collapse. The situation is under control and a team of experts is taking proper care of it.”
Italian Undersecretary of State for Culture Lucia Borgonzoni said the situation was worrying and appeared to blame the city council for allowing the danger to arise.
“Perhaps the municipal scientific committee in charge of preserving the tower underestimated the situation,” Ms. Borgonzoni said in an interview with Quotidiano Nazionale.
She added: “The government has decided to save the famous Bologna Tower after the city council wasted time.”
The tower was one of the last remaining medieval towers in Bologna. It was poorly built and was already considered to be in danger of collapsing in 1350
What is the Leaning Tower of Pisa?
The medieval tower, known for its five-degree slope, was originally built in 1173 as a bell tower.
At eight stories and 183 feet tall, the marble and stone structure was so heavy that it began to sink into the soft earth.
The architects tried to compensate for this by making the walls higher on the sinking side, but this only made the problem worse.
The structure was strengthened in the 1990s with work that brought the slope under control.
Ms Borgonzoni also announced that the government would fund work to strengthen the tower with around €5m (£4.3m) from Italy’s national EU recovery fund.
The Garisenda Tower was built between 1109 and 1119 by one of Bologna’s rival families, who built ever taller towers as a sign of their wealth and power.
At the height of the building boom, Bologna had up to 200 towers of varying sizes, serving both as defenses and for signaling in times of danger.
However, during major renovation work in the 1920s, many towers were razed to the ground, so only a handful of towers remain today.
One of the city’s famous “two towers,” it is dwarfed by the neighboring Asinelli Tower, which nearly doubles its height at 318 feet (97 m).
Unlike its larger neighbor, the Garisenda Tower has been in danger of collapse almost since construction was completed.
In the 13th century, the Italian poet Dante noted that the tower had sunk drastically and by 1350 the top 10 m had to be removed to prevent collapse.
The city’s tourism authority says the tower is not likely to collapse at this time, but that teams of experts have been brought in to assess what conservation measures are needed
Similar to most of Bologna’s medieval towers, the Garisenda Tower was built on a ring-shaped base made of mortar terracotta bricks and river stones.
This base material is likely the cause of the tower’s drastic tilt, as the foundation sinks into Bologna’s soft soil.
Nunziante Squeglia, an expert at the University of Pisa, says that both Pisa and Bologna have a similar problem with poor soil conditions for construction.
“Bologna, like Pisa, is built on one level and there is a problem with soft clay soil,” Mr. Squeglia told the Times.
The properties of this soft clay combined with the poor construction of the tower’s foundation caused Garisenda to simply sink into the earth and fall to its side.
Others blame the city council’s decision to allow traffic around the base of the tower and claim that vibrations from passing vehicles may have further destabilized the foundations.
Raffaele Milani, head of the Italian heritage group Italia Nostra in Bologna, told the Times: “We have been saying for years that the area should be made pedestrian.”
In 2019 the council placed iron bands around the tower base and in 2022 mortar was injected into the foundations.
However, these interventions do not seem to have been successful, as the Garisendi Tower is now more at risk of collapse than ever.