Scaffolding and netting have been assembled as a precaution around both central-city buildings, because both are due for more remedial work.
Nobody was hurt in the recent incident.
Dunedin City Council property services group manager Dave Bainbridge-Zafar said a heritage architect and specialist stonemason would investigate the buildings’ exterior to determine what needed to be done in the short term.
The Municipal Chambers in the Octagon opened in 1880.
Mr Bainbridge-Zafar said this week the council did not yet know if the stone that fell was part of the original stonework.
"A thorough check of the building is yet to be carried out, but results are expected by early next year," he said.
"In the meantime, the netting and scaffolding are in place as a precaution."
The town hall, behind the chambers, was built in 1929.
The cost of temporary scaffolding and netting is about $50,000.
