The Southland Masonic Centre in Invercargill has been sold to a North Island company.

Southland Real Estate agent Graeme Ridder said the sale went unconditional last week after an approximately three-week negotiation period.

Mr Ridder wouldn't name the buyer, only saying it was a North Island property company.

The Greek revival-style building was completed in 1926, and was made a Category 1 heritage site in 1984.

Heritage New Zealand says it is a "highly significant building" and "probably the most impressive of any lodge building in the country."

Mr Ridder said the Freemasons who used the building were thinking of re-locating to a more "user-friendly" building.

"The Temple and everything in that building's upstairs and it's quite a haul for them. A lot of these folks are [in their eighties] now."