The Colosseum is open to visitors as usual after three pieces of mortar measuring around half a square metre in total came loose from a ground-level gallery early on 9 May and fell to the ground. The fall was partly cushioned by protective netting below. Tests are being carried out on the fragments to establish the exact cause of the collapse, but a preliminary assessment of the damage suggests that a combination of vibrations and pollution are to blame. Specifically air pollution is thought to have changed the chemical composition of the mortar, causing pieces to break off.

The incident has brought back to public attention the poor condition of the first-century AD amphitheatre and renewed calls for a suspension of concerts and a reduction of traffic in the area.

In March the culture minister announced a large-scale cleaning of the outside of the Colosseum at a total cost of