Craigmore House in Herne Bay has no protection and is currently for sale.
Some of New Zealand's grandest and most admired historic homes have no protection and could be destroyed to make way for multiple townhouses.
Large, well-known properties in established areas of Remuera, Herne Bay, Mt Eden and St Heliers are currently listed for sale and heritage experts say they have been made targets as a result of planning changes in Auckland.
The homes are described in the listings as a "developers dream" or "maximum gain and return".
That is worrying Character Coalition head Sally Hughes, who said the Unitary Plan needed to include a requirement for resource consent and public notification for any pre-1940s demolition.
The current plan had given the go-ahead for "historical vandalism", she said.
Two historically significant homes - one on Argyle Street in Herne Bay and another on Springcombe Ave in St Heliers - are "cultural treasures" but could be lost forever depending on who buys them, Hughes said.
Marketing material for Craigmore House, a grand six-bedroom Herne Bay home built out of kauri, describes sweeping staircases and beautiful arches.
Also highlighted is the "flexibility" of the 2107sqm of land, with a council valuation of $8.2 million.
The blurb, by NZ Sotheby's International Realty agent Pene Milne, said the land is in the Residential Mixed Suburban zone, which allowed multiple lots.
Hughes said losing a property like Craigmore House in Herne Bay would be "really distressing for those of us who care for historic heritage".
"It is absolutely cultural vandalism - it is an amazing property that is part of the history of Auckland.
"To lose it would be criminal."
Hughes said 9 Springcombe Rd was an important part of the story of St Heliers.
"That area has a rich history and that house is part of that history - and it could be lost."
In his marketing of the sprawling home on Springcombe Rd, agent Don Ha encourages buyers to either live in the home or "take full economic advantage of this mammoth-sized property".
"Develop a row of luxury town houses or apartment living, or maybe shoot for higher site intensity," he says.
Another agent selling Springcombe Rd, Ricky Cave of Ray White, points out there is already "resource consent in place to remove the grand villa currently occupying the 3037sqm site".
Auckland Council manager resource consents central Mark White confirmed 9 Springcombe Rd and Craigmore were not protected and could be removed without resource consent.
Other significant properties such as three historic villas side by side at 199 Mt Eden Rd, two 1920s bungalows at 15 and 17 Amaru Rd, One Tree Hill, are also highlighted for their development potential.
Hughes said finding the council had given the green light for 9 Springcombe Rd to be removed brought back memories of the stately Coolangatta homestead at 464 Remuera Rd that was demolished with antique furniture still inside.
The demolition of the Coolangatta home and three Spanish mission style homes side by side on Turua St in St Heliers was behind the formation of the Character Coalition.
Hughes said too many people assumed large character homes, landmark buildings and properties of significance were protected.
"But very few are, hardly anything in Auckland is protected," Hughes said.
The Character Coalition argued large estates and character buildings would be lost during discussions with the panel for the Unitary Plan and were told it would rarely happen.
"They argued it was not likely but it's human nature to want to maximise profit and that it is what this issue is.
"It is maximising private wealth at the expense of Auckland suburbs. Character and amenity and value of suburbs will be lost for private profit."
This week Hughes and colleague Alex Dempsey revealed they were collecting and presenting data to Prime Minister Jacinda Ardern in her capacity of Minister of Culture and Heritage.
"We spoke with the Prime Minister and she put us in touch with her senior officials at the ministry and we have been supplying them with all of this data," Hughes said.
"They asked us to gather the information and they are currently doing work [on] this particular issue - that the current Unitary Plan allows this loss of cultural heritage."
Hughes said the organisation "had been very heartened" by the Government's engagement on the issue.