Bayleys real estate agent Peter Sullivan did not want to speculate on what the site might sell for, but said the owner had had multiple offers from developers for more than it was worth.
The site, on which Mr Bosher is still operating his 700-plus sheep farm, is 27.7 km from central Auckland and zoned for high and low density housing and could support more than 300 houses, according to Mr Sullivan.
"It's probably one of the largest development opportunities available today, definitely one of the largest in Flat Bush ever to be offered," he said. "It has fantastic panoramic views of the city, which are rare to find in Flat Bush."
"It's probably one of the largest development opportunities available today, definitely one of the largest in Flat Bush ever to be offered," he said. "It has fantastic panoramic views of the city, which are rare to find in Flat Bush."
The site will also overlook the soon-to-be-built $500 million Ormiston Town Centre. The 19ha hub will include retail stores, commercial offices, medical facilities, restaurants and cafes, recreational space and an aquatic centre.
Mr Sullivan said it was hoped the area would be declared a "special housing area" under the council's Auckland Housing Accord, which fast-tracks building consents. About 39,000 new homes and sections are expected to get consents during a three-year period.
The first lot of special housing areas was announced in October, with a further 11 announced in December. Individual landowners can request their land be among the areas, but the council is also identifying its own sites. A 7ha site on the same road has already been declared one of the areas, as has a 37.8ha site on nearby Murphys Rd.
The 61ha is being marketed to developers internationally. It is expected to be subdivided with sections starting at 400sq m.
Mr Sullivan said the town was thriving and sections of 400sq m were selling for more than $500,000.
Mr Bosher, 87, said it was time for his family to sell.
"I've been farming now going back to the 1960s. That's how long we've been here. I decided at my tender age we might sell a big part of it. I'm not 21 any more, I'm getting on a little bit."
He said it would be sad to say goodbye to the land.
"It's a lovely place, it looks right over a fair bit of Auckland ... It's some of the nicest land in Auckland."