The tragedy has left four people confirmed dead and a fifth person who is missing feared dead.
Three others were injured.
Rescue workers are reportedly still trying to recover the body of the missing person.
In Florence, a minute of silence was observed at 3 p.m. local time, with Mayor Dario Nardella present outside the city hall in Piazza della Signoria.
Public transport operators Autolinee Toscane and Gest had vehicles decked out in mourning while the tramway stopped for a minute, also at 3 p.m.
Earlier in the day, shops closed at midday for 15 minutes and employees stood outside in memory of the victims.
“I don’t remember such a serious workplace incident in our city, which is attentive to workers’ rights,” said Nardella after visiting the Esselunga supermarket construction site in Via dei Mariti.
The sight of “the beams, these concrete blocks” made a “very heavy impression”, he added.
The incident has put workplace safety in Italy back in the spotlight.
ANSA
