"Police will be in touch with the building's owners to discuss next steps.
"Inquiries are ongoing to determine the circumstances of the fire, including whether there may have been anyone in the building."
The building, at 128 Abel Smith St in Te Aro, had recently been used as the headquarters of The Lebanese Society of New Zealand (Inc) and was a community centre for generations of activists before that.
A colourful history
The building was designed by William Crichton and built in 1898.
Secretary for the group, Stephen Wakem, said: "Many of our members are children or grandchildren of the original 1946 membership in Wellington and we're sad to lose a piece of our local legacy.
"In those early days, the building was a hub for bringing together Lebanese in shared identity - which is something we have been trying to achieve since we reinstated the society's membership a couple years ago."
The building also served as a temporary home for members of the Lebanese community who had just arrived to Wellington.
"By the early 2000s, society membership had substantially reduced and the premises no longer had the same use and function as it once enjoyed," Wakem said.
In 2007, the building was raided by police investigating allegations of terrorist training camps in the Urewera.
Another community group - The 128 Collective - used and cared for the premises afterwards, before The Lebanese Society recovered the premises last year.
A committee had since been working with society members to decide on the building's future, Wakem said.