Garisenda
The Garisenda tower in Italy. Image: Ввласенко, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Garisenda tower in Italy's Bologna has been sealed off after experts warned that the 900-year-old tower might fall.

The tower is also known as the "leaning tower," but it is not the iconic Tower of Pisa, which leans at 5 degrees. This 14th-century tower leans at an angle of 4 degrees. The authorities have said that "the tower is at great risk of falling, so we need to be ready for every eventuality".

The city council has decided to build 2.6-metre-thick barriers around the base of the tower to contain its debris. The construction will cost around £3.7 million. A crowdfunding campaign has also been launched by the city authorities for its restoration and protection. The restoration work will continue for several years.

"A protective cordon will be erected to contain debris resulting from a possible collapse, to reduce the vulnerability of surrounding buildings and the exposure to the population, as well as blocking access to the off-limits areas," said the city council in a statement.

Earlier, some reports had claimed that the square surrounding the Garisenda tower will be closed for a few years due to the fears that the tower might collapse. The city's mayor had also said that it was necessary to close Piazza di Porta Ravegnana to "save" the Garisenda tower, per a report in The Guardian.

"We're not intervening because we think it could collapse at any moment, we're intervening because we want to make it safe and restore it," he added.

The latest warning has been issued by a committee of scientists and experts that has been monitoring the site since 2019. The monument was first closed to the public in October after sensors detected changes in its tilt.

The warning says that an "unexpected and accelerated trend" of "crushing compression" of the base tower has been observed. The civil officials closed all roads leading to the tower soon after the warning was issued.

The Garisenda Tower is one of two towers located in Bologna. They were built between 1109 and 1119. Garisenda's height was reduced in the 14th century because it had already begun to lean.

The Leaning Tower of Pisa, meanwhile, began to lean during its construction almost 850 years ago due to the soft earth beneath it. It was closed for restoration in the 1990s, and engineers worked on the structure to stabilise it. The project cost around £25 million and took 11 years to complete.

The local authorities claim that the tower is in great health and is slowly losing its tilt, according to a BBC report. It has lost 4cm of its lean in the last 20 years.