Bologna has decided to seal off a historic square following fears that a 48-metre-high iconic tower in it risks collapsing.

Piazza di Porta Ravegnana is being surrounded by a 5m-high wall made out of shipping containers intended to protect people and buildings from the risk of Garisenda Tower collapsing.

The 12th-century tower is, together with its taller cousin and neighbour Asinelli Tower, an iconic part of the Italian city’s skyline.

Authorities in the Italian city said the situation is highly critical and that intensive structural works are needed before the tower can be considered safe.

Those works are expected to take several years to complete and Bologna’s cash-strapped city council has launched a crowdfunding project to finance them. As of Friday, that public appeal had raised €800,000.

Aside from planning emergency works, the council is also considering other measures to protect the towers. One of the ideas that has been floated is to ban buses from driving past the area, to reduce vibrations.

In the meantime, authorities are sealing off the tower by building a 5m-high container wall around it, intended to catch any debris that might fall and protect people and nearby buildings should the tower collapse.

The wall alone is projected to cost €4.7 million to build.

Garisenda Tower’s leaning problems are not new: the tower was originally 60 metres tall but reduced in height less than 100 years after it was first built due to structural concerns.

Structural engineers have been keeping a close eye on it in recent years and problems became more acute in October, when inspections and sensors revealed that its foundations were in poor shape and rapidly deteriorating.