It's the French Ambassador's residence, which is worth a mint. (I like the bit about Sean Dunne making his fortune in the law courts.) More here:

Friday January 18 2008
IT'S a complaint most home-owners will not have heard before. As the French Ambassador's sumptuous residence in the heart of Dublin goes on the market with an exclusive price tag of €60m, he revealed the home is so vast he has to send out an SOS on his mobile phone to locate his wife.

The French Government has decided to sell the property, which boasts one of the most sought after addresses in the country at Ailesbury Road in the heart of Dublin's "Embassy mile''. It's Chancery offices across the road, with a mere price tag of €20m, has also been placed on the market.

The vast 40-room house, number 53, formerly known as Mytilene, sits on just under two acres and covers 11,450 sq ft of living space. It boasts a cellar of French wine, countless fireplaces, the first-floor private quarters of the Ambassador, a restaurant fit for a Michelin- star chef and a major drawing room for entertaining.

As the house, which dates from 1900 was put on the market, Ambassador Yvon Roe D'Albert, who is only in the post for six-months in Ireland, said it was a fabulous location for hosting events, with a dining room capable for comfortably seating 45 people and a drawing room which would hold 120 guests. However, he said it may not suit families. "It's so big, I have to call my wife on her mobile phone if I want to talk to her," he revealed.

According to Lisney's John O'Sullivan, there is "disbelief in the city that it is going on the market" after almost 80 years in the ownership of the French Government. He added: "We have been dealing with very interesting inquiries already."

That leafy region of the capital is already home to a number of wealthy developers such as Sean Dunne, and others who have made their fortunes in the law courts and technology companies.

As part of a worldwide downsizing move, the French Government has decided to sell off a number of properties. However, they will be looking for an alternative accommodation for their Ambassador and offices for staff in the Ballsbridge area. It is believed they may consider exchanging the property for an alternative building plus cash.

The Ailesbury Road house also claims a colourful history of a rags-to-riches story. Around 1840, a homeless boy, who was selling newspapers at Donnybrook Fair in Dublin, found a large sun of money. After tracing the owner, he was rewarded for his honesty. George Bustard then set sale for Australia where he made his fortune. He never lived to realise his dream of building a house close to the fair. However, he left strict instructions in his will for his family to pursue his wishes, even down to using the expensive white stone which makes the residence unique on the road.

The house was purchased by the French Government in 1930.