Spectacular century-old castle with a dungeon and a stone turret with uninterrupted views of Sydney goes on sale for $25MILLION

A century-old castle with a turret and a dungeon is expected to shatter Sydney's North Shore property price records when it hits the market next week.

Tucked away on 8,000sqm of land overlooking Middle Harbour, the exclusive surrounding suburb of Castle Cove derives its name from the Heritage-listed Innisfallen Castle.

Real estate agents are confident the historic property built in 1903 by a distinguished member of Australia's first parliament, will sell for well over $25million.

Tucked away on 8000 square metres of bushland overlooking Sydney's Middle Harbour, the Heritage-listed Innisfallen Castle will hit the market next week

Real estate agents are confident the historic property built in 1903 by a distinguished member of Australia's first parliament, will sell for well over $25million

Although Australia's housing sector has taken a hit since the onset of the coronavirus pandemic, the luxury end of the market prices have continued to soar.

That's why sellers predict the ultimate trophy home will garner a massive amount of interest from top-end buyers hoping to live out their royal fantasies.

'It's hard to know exactly what the home will sell for but the most expensive home ever sold on the north side of Sydney is $25million,' Michael Pallier from Sotheby's International Realty told 9News.

'We expect this home to sell for more than $25million.'

The castle has stunning 360-degree views of Sydney from atop its three-storey stone turret.

It also features a tennis court and a rear courtyard overlooking the ground's rolling green lawns.

The underground space, formally a dungeon, has now been turned into a modern wine cellar and gym, and could even be set up to include a sauna.

The property features a tennis court and a rear courtyard overlooking the ground's rolling green lawns

Real estate agents are confident the historic property built in 1903 by a distinguished member of Australia's first parliament, will sell for well over $25million

The castle has stunning 360-degree views of Sydney from atop its three-storey turret.

Several elements of the property still remain including the original gardens, long driveways, stone edgings, three-foot thick walls, stained glass windows and several paintings.

Although the man who built the castle was no king, he was a founding member of Australia's first parliament.

Henry Willis was a founding member of Australia's first Parliament

Henry Willis married Annie Louisa Moore in 1889 and was elected to the Australian House of Representatives in 1901 as a Free Trade Party member for the division of Robertson.

Shortly after, he acquired 21ha of land and got to work on the sandstone castle.

The couple went on to have five children.

According to the NSW Office of Environment and Heritage - which granted the British-inspired castle a Permanent Conservation Order in 1988 - up to 40 men worked on the building for about three years.

Many of the workers lived on the site in tents with their families as the home was being constructed.

Mr Willis named the Innisfallen Castle after a ruined Abbey in Ireland's Killarney which means 'Isle of the Field.'

The property remained in the family up until 1988 and has only ever changed hands twice.

'The Willis family occupied themselves with light farming, and lived a relatively rustic lifestyle until the 1960s during which time, the estate was subdivided and the original house was connected to town water and electricity supplies,' the NSW Office of Environment and Heritage said.

The underground space, formally a dungeon , has now been turned into a modern wine cellar and gym, and could even be set up to include a sauna