Three fluffy white chicks were spotted in the nest, which had been made inside a crevice just below the roof of the 14th-century bell tower.
Filmed by workers inspecting the tower from a crane, the chicks immediately began calling for their mother, who was seen circling overhead.
The crew wisely made a retreat and left the family of falcons where it was as they continued their task of checking the tower's facade to make sure that its colored marble panels remain securely in place.
Watch the video here:
Video: Andrea Lattanzi/Repubblica
The bell tower seems to be popular with peregrine falcons, who have been seen nesting in it on several occasions in the past, apparently undeterred by the crowds of tourists who climb the 414 steps to its roof.
To judge from their white down, these falcon chicks are less than a month old. They will remain in the nest for another three weeks before they learn to fly, hunt and eventually strike out on their own towards the end of summer.
The birds are widespread in Italy and can be spotted gliding over the roofs of many cities, including Rome, where they prey on the millions of migrating starlings that plague the capital with guano (not to mention creating a glorious natural spectacle in the sky).
Giotto's Campanile, one of the landmarks of the Florence skyline alongside the domed cathedral, gets a three-week safety inspection once every six months.
The importance of maintaining Italy's heavily visited and fragile heritage was tragically highlighted last autumn, when a chunk of stonework came loose from the walls of Florence's Basilica di Santa Croce and struck and killed a Spanish tourist.
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Photo: Tiziana Fabi/AFP