Part of the footpath in Hanover St has been closed since Sunday night after part of Hanover Hall's parapet crumbled and fell on to the ground below.
Cally McWha and Lloyd Williams bought the early-1900s building in 2015 so it could be used by the Dunedin Symphony Orchestra.
As it had a category one historic places listing, she called Heritage New Zealand so it could assess what happened.
After a report was completed she would likely need someone to go up in a cherry picker to see if there were any cracks and potentially remove loose stone.
She did not know when this would be.
The fallen stone was unexpected as when the building was bought an engineer's report by Hadley Robinson said it was more than 90% compliant with national building standards.
''We would not have bought it otherwise.''
A council spokeswoman said it had assessed the incident and the property owner was dealing with the issue.
Before the building was bought in 2015 it had been the nightclub Monkey Bar and the Hanover Street Baptist Church.