Three pieces of mortar -- measuring half a square meter (yard) -- collapsed at the weekend in the ancient amphitheatre, one of the most popular sites in Rome, plunging through a protective netting.
It was the latest in a string of collapses in the forum, where ancient Romans came to watch gladiators fight and see massive spectacles staged, raising fears about visitor safety and whether the buildings can remain standing for much longer as water leaks from rain undermine their foundations.
A restoration and cleaning project is set to start within the next month at the Colosseum, which was completed in 80 AD, but the city council is still struggling to raise all the funds needed from the private sector and from donors abroad.
We have already organized work on all areas around the three rings of the Colosseum, the first, second and third floors, which will be completely restored under this project involving conservation work for 23 million euros said the under-secretary for Italy's heritage ministry, Francesco Giro.
In March, part of the ceiling collapsed at the nearby Palace of Nero, or Domus Aurea -- which has been plagued by structural problems since it was opened to the public in 1999.
Conservation, preservation and restoration is needed in the Colosseum and many other places, said Darius Arya of the American Institute for Roman Culture.
It is very difficult because these are not pieces and artifacts that are inside a museum, they are outside in the open with the rain and the noise and all these tourists walking around. So these are places that need even more money than most people can imagine, he added.