PHOTO: The $17.5 million property has been transferred from Chinese billionaire Wang Qinghui to 17-year-old Caleb Wang. Photo: Supplied.

It was the best Christmas present a teenager could hope for – a Sydney mansion worth a whopping $17.5 million.

And it now leaves one of the country’s most stunning historic homes in the hands of a young man still not yet old enough to buy alcohol, get a tattoo without his parents’ permission or even to apply for credit to purchase his own house.