The Pozzo di Borgo family who are selling the most expensive house in Paris will miss the parties the most, says Lara Marlowe

HOW DO you put a price-tag on 300 years of French history? The Hôtel de Maisons puis de Soyecourt, built in 1707, is the best preserved 18th century mansion in the Faubourg Saint-Germain, the left bank neighbourhood where the French aristocracy lived. Most of the surviving mansions have become government ministries or ambassadors' residences, and it is extremely rare for one to come on the market.

One owner, a de Soyecourt, was guillotined in the French revolution, but the property has brought good fortune to its owners since 1836, the Pozzo di Borgos, a family of Corsican nobles who trace their lineage back to the 12th century.

With an asking price of approximately €100 million, the 3,800sq m (40,902sq ft) property is easily the most expensive residence in Paris. It is like a miniature château de Versailles in the heart of the city. One enters from the rue de l'Université, beneath a grand archway. There is a large cobblestone courtyard, flanked by two concierge's lodges. The courtyard is dominated by the harmonious two-storey, 18th century facade, made of hewn stone and paned windows, with a central pediment and pilasters.

Another wing, in the same style, was added along the left side of the courtyard in the early 19th century. An archway leads to a second cobblestone courtyard shaded by a large tree. The surrounding buildings, contiguous with the main house, were once stables and servants' quarters. Today they house 450sq m (4,844sq ft) of office space and seven apartments.

The south side of the house looks onto a 2,600sq m (27,986sq ft) garden, planted with a lawn and mature trees. Footpaths meander through exotic shrubbery, and a seven-metre high wall ensures privacy.

The most famous Pozzo di Borgo was Count Charles-André, a Corsican general who was pursued across Europe by Napoleon Bonaparte, became the Czar's ambassador, restored four Bourbon princes to their thrones and was posthumously given an Italian dukedom. Present-day Pozzo di Borgos include a writer, a costume designer, a photographer and a French ambassador.

Count Alexandre Pozzo di Borgo, an advertising executive and events organiser, and his cousin, the future duke Reynier Pozzo di Borgo, an architect, are my guides for the visit. Both men are refreshingly informal, and even joke about their titles.

"We've travelled a lot," explains Reynier. "A title looks good on a calling card, but merit is better." Thirty people, three generations of the Pozzo di Borgo family, still live in the house, and their arrangement is worthy of a Balzac novel. The relatives are divided into five households, most of them in the former servants' quarters, which have been converted into comfortable apartments.

"We leave our doors open. If you run out of noodles, or butter, or sugar, it's great - you just cross the landing," says Alexandre. The family meet in the elegant reception rooms for birthdays, christenings and Christmas.

Alexandre shows me an 18th century glass window pane, turned milky-white by age. "All the others got broken when we played ball as children," he laughs. "We ran every which way. We rough-housed in the garden . . . You almost didn't need friends, because the whole family was here. We've been lucky to live all together, to have our grandparents help raise our children."

"We'd love to stay; it works well," says Reynier. "But there are 12 heirs in our generation, and if one of us dies, we couldn't pay the death duties. The tax authorities would say, 'Ah! The house is worth X', and it would affect the inheritance of the other eleven."

The two men laugh when I ask how many rooms the property contains. "We never counted!" says Alexandre. After a brief calculation, he says it has been divided into 18 parcels, ranging from a studio to apartments of 240sq m (2,583sq ft). There is also a 700sq m (7,534sq ft) wine cellar, to be sold without its contents.

The finest, oldest, part of the house, about 1,000sq m (10,763sq ft) , is presently rented by a high fashion designer. Remodelled in 1750 by the architect Mouret, it contains spectacular Louis XV reception rooms with gilt mouldings that were carved directly into the wood (later mouldings were papier-mâché) by a royal sculptor.

Throughout the house, there are countless frescoes, marble fireplaces, crystal chandeliers, and exquisite parquets. A grand staircase with filigree wrought iron railing leads from the main entry.

The 19th century reception rooms are decorated in the same Rococo style, and are filled with the treasures of the Pozzo di Borgo family - including vases given by the Russian Czar to their ancestor, Count Charles-André. Cleaning men are still tidying the long music room in the 19th century wing, where musical instruments are sculpted in elaborate gilt mouldings. "We held a party for 300 teenagers on Saturday," explains Alexandre. "There was a stage for the musicians, strobe lights, a 1,000sq m (10,763sq ft) marquee in the garden . . ."

"This house comes to life when it's full of people," says Reynier. "At night, it is pure magic."

The Hôtel de Maisons has always been a place of lavish entertainment. The Duc de Saint-Simon recorded that its 18th century owner, the Marquis de Maisons, "was happy to live with the best company from court, who his wife and he had drawn to them with the most polished manners". The marquis left the house to his son Jean-René, a friend of Voltaire.

"Parisians always looked forward to our balls," Reynier recalls with a tinge of nostalgia. "There were superb balls here; we had such a good time!" He and Alexandre have especially fond memories of a ball given by Alexandre's sister Barbara in the early 1970s. The theme was Johann Strauss' Vienna.

"Everyone was seated for dinner and we heard a clanking sound, " says Alexandre. "It was a guest who arrived in a coat of armour. Everyone thought he'd gone to the wrong party." As children, the cousins took classical dance lessons in the music room, while their grandmother played the piano.

The same grandmother inherited two Stradivari violins, which she lent to the Paris conservatory. Every year, the conservatory put on a concert in the house.

The house was perhaps the first example of another modern tradition: the property speculator. A certain Francois Duret purchased the land from the abbey of nearby Saint-Germain-des-Prés, and had the house built in 1706-1707 for the sum of 93,000 pounds.

Over the next quarter century, Duret snapped up land throughout the Faubourg Saint-Germain, hired the best architects, then sold the mansions as they neared completion.

During the Paris Commune in 1871, the revolutionary women known as pétroleuses burned down many of the fine houses of the Faubourg Saint-Germain. "When the mob reached our front gate, their leader ordered them to stop, because he was Corsican," Reynier recounts.

Reynier has just translated historian John M P McErlean's book Napoleon and Pozzo di Borgo into French. He says their rivalry was rooted in Pozzo's loyalty to Pasquale Paoli, considered the father of Corsica. Napoleon's father Charles had been Paoli's secretary when they fled to London after an uprising against the French. But Charles Bonaparte betrayed Paoli by facilitating his wife's affair with a French nobleman.

That, says Reynier Pozzo di Borgo, was the origin of the century-long rift which gave the Pozzo di Borgos an enduring reputation for opposing the Bonapartes. In the 1850s, General Patrice MacMahon - who was of Irish origin and later became president of France - wanted to marry a niece of the Pozzo di Borgos. But because MacMahon served Napoleon III, Duke Pozzo refused to allow him to attend the family's grand ball in the Hôtel des Maisons.

When the Duchess threatened to leave the house forever, the Duke relented and the engagement was finalised at the ball. Today, the Pozzo di Borgos and Bonapartes are reconciled. Prince Charles-Napoleon, the pretender to Napoleon's throne, even prefaced Reynier Pozzo di Borgo's translation of Napoleon and Pozzo di Borgo.

Perhaps an Irish, Russian, or Arab billionaire will purchase the Hôtel de Maisons. Several hotel chains have considered the property, but were stymied by the prospect of obtaining planning permission and knowing what to do with all those ballrooms.

It would be ideal for a combined ambassador's residence and embassy.

Conseil Immobilier International

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