The 20.4m by 3.6m mural was found behind hardboard walls in May during demolition of the hall and it was believed it had been created in 1892 for a Japanese-themed festival.
Since the mural was discovered, architectural conservator Guy Williams and representatives from the Historic Places Trust, the Dunedin City Council, the Dunedin Public Art Gallery, Port Chalmers Historical Society and the Otago Settlers Museum have been researching the work and looking at ways it could be saved.
Mr Williams said yesterday the group had decided the mural should be taken down so the demolition of the hall could continue.
"It is a very rare artefact. The only one been found in New Zealand of its type."
It would be a "tedious and a bit dirty" job for the art conservators involved and just how it would be done was still to be trialled, he said.
The initial plans involved cutting the nails, still attached to the mural, flush with the boards and then rolling it up and cleaning it at the same time.
"We're still working out the finer details."
It would then go into environmentally controlled storage until long-term conservation and funding decisions could be made, Mr Williams said.
"At the moment, it is important enough to remove as much of it as possible."
