Built in 1853 with New Zealand native wood, its design is influenced by American architecture.
"John Harding, the original who built the house, was a great admirer of George Washington and we've been to see the Mt Vernon in America, they're very similar."
Mr Harding says the family has always been passionate about Māori culture, and there are paintings of Māori figures to demonstrate this.
Also, paintings which John and Emma Harding bought when they first established the home will likely remain in situ long after the Harding's have left.
"All our history is here, which is quite unusual, having never thrown anything out all our family documents here, right back to the 1840s," Mr Harding says.
"As long as they (new owners) respect the heritage, that's the most of it."
Among other features, the house has a pool, a tennis court, a library, a converted wine cellar museum - and Mr Harding's favourite.
"The drawing room, it likes a good party and it's got the fantastic fire which warms the place up and it's just a comfortable room, we love it."
Mr Harding would prefer another family buys the house.
But, no matter who snaps up the treasure, he's confident his ancestors buried in the on site cemetery will keep a watchful eye.
"There's not many people who have their own cemetery I don't know if it's a plus or a minus."
The house, lawns and even trees are protected, so, even though the Harding family is ending a years-long chapter, they can be sure their history will live on through Mt Vernon's next chapter.
The sale is price by negotiation. Mr Harding didn't say what the family expects to get for this unique piece of New Zealand architecture.