Villa Leopolda in Cap Ferrat (above), once the world's most expensive estate with a $750 million pricetag, may now only be worth $40 - $50 million thanks to plunging prices in the wake of the global recession, according to Sotheby's International Realty CEO Alexander V. G. Kraft. "For trophy properties it used to be a question of how much someone was willing to pay," Kraft tells the London Telegraph. "They would come quietly onto the market – they would be marketed under the table. This system really has totally collapsed. Buyers willing to pay anything like those sums just don't exist anymore." The paper says "panic sales" are on the rise in the ritzy area.

As we wrote about back in February, Russia's richest man Mikhail Prokhorov had reportedly agreed to purchase the Villa for $750 million but later backed out of the deal, forfeiting a $55 million deposit. The estate has not been re-listed. "Prices are coming more in line with the rest of the market," Kraft declares. "Trophy properties will be more in line with 'normal luxury properties' – about 20 to 30 million [euros]." Peter Ilovsky, director of Sotheby's International Realty in Cap Ferrat, says they're still good investments however. "Owning a property in Cap Ferrat is like having a Picasso," he tells the paper. "It's certainly better than placing the money in a Swiss bank."

Five months ago when Forbes ranked the world's most expensive houses (in terms of current listings) only three of them clocked in at over $100 million. And in fact, one of those, Leona Helmsley's Dunnellen Hall in Greenwich, CT which started out at $125 million had already been reduced to $95 million by the time the list was published (it's currently being offered at $75 million). The other, Fleur de Lys in Beverly Hills listed at $125 million, was therefore the world's most expensive and one of only two $100 million-plus properties officially on the market.

Re-surveying the field now we've decided it's time for a new World's Most Expensive list, mainly because despite the recession - or, perhaps, because of it - there are now seven properties in what we've dubbed the Hundred Million Club (N.B. - those listed at only $100 million don't make the cut), three of which are in the U.S. These are the modern-day equivalents of the magnates' great estates we wrote about back in February.

Some recent market activity which regular Luxist readers will be aware of makes a new ranking imperative. For starters, last month Candy Spelling listed her Holmby Hills mega-mansion at $150 million, making it the world's most expensive estate. Then just last week a mansion at No. 10 Belgrave Square in London hit the market for around the same price - £100 million, or about $149 million (depending on exchange rates), while a second Belgrave Square property finally completed renovations and has been listed at £80 million, or about $120 million.

We also received confirmation this week that an incredible 40-room private mansion in Paris' Place des États Unis (above), built in 1890, has been listed at €105 million, or about $138 million. Fleur de Lys, whose "world's most expensive" status (though not its "legendary estate" status) was also usurped by the $135 million Manaplan Residence in Palm Beach now languishes in 5th place (sorry, Mariah).

Here is our new ranking of the world's most expensive estates (in terms of current verifiable listings), all members of the Hundred Million Club:

1. The Manor - Holmby Hills, CA: $150 million
2. No. 10 Belgrave Square, London, UK: $149 million
3. Place des États Unis, Paris, France: $138 million
4. The Manalapan Residence, Palm Beach, FL: $135 million
5. Fleur de Lys, Beverly Hills, CA: $125 million
6. No. 31 Belgrave Square, London, UK: $120 million
7. Updown Court, Surrey, UK: $110 million

The mystery surrounding who might have bought Villa Leopolda continues. The lavish home in Villefranche-sur-Mer, south-eastern France was on the market for a record price of 390 million euros. Last year rumors swirled about the rich Russian who bought the home. We went through a laundry list of billionaires before learning that the most likely candidate was Mikhail Prokhorov, currently Russia's richest man. He denied springing for the home but as my colleague Jared Paul Stern learned last month, Prokhorov reportedly signed a contract on the property and paid a $55 million deposit, but wanted his money back.

The villa's owner, Lily Safra, has no intention of letting that happen and she made it public last week by issuing a press release saying that she would donate money to ten charities using "all proceeds potentially available from a deposit made on the sale of Villa Leopolda, which has now been halted." King's College, London, and Imperial College, London would each receive one million euros neuroscience research. Safra doesn't name who the buyer might have been in the release. The home is no longer on the market which is probably for the best since the list of people with the funds to purchase such a home continues to dwindle.

It seems that Russia's new richest man, Mikhail Prokhorov, may not have been telling the whole truth when he denied buying the world's most expensive house, the $750 million Villa Leopolda (above) on the French Riviera, last year. Back in August we reported that the metals magnate was the mysterious purchaser of the eye-popping property, but Prokhorov, who's worth $14.1 billion, protested his innocence, saying he declined to do business in France because of a mix-up with some prostitutes and the French police. Now the London Times reports that Prokhorov signed a contract on the property and paid a $55 million deposit, but wants to back out of the deal.

Prokhorov reportedly lost $7 billion in the economic crisis but has fared better than fellow oligarch Roman Abramovich. Prokhorov will likely face a legal battle over the deposit, which is non-refundable under French law, with the Villa's seller Lily Safra. "Lily is adamant that she's not handing the deposit back," a source close to the deal tells the London Daily Mail. "Mr. Prokhorov, in turn, claims that property prices have collapsed since August, and the figures originally discussed were unreasonable. He wants out, and he wants his money back." We expect Prokhorov, founder of a new magazine for snobs, will likely issue another denial this time as well.

Now this is just getting ridiculous. First Roman Abramovich was rumored to have bought Villa Leopolda, the pricey estate in Villefranche-sur-Mer on the French Riviera. Then Russian precious metals mogul Mikhail Prokhorov was said to have snapped it up. As my colleague Jared Paul Stern reported over the weekend, Prokhorov is the 24th richest man in the world with a $22 billion fortune and was briefly detained during an investigation into a suspected prostitution ring at a ski resort in the French Alps. Turns out Prokhorov still has some hurt feelings over that bit of police drama says BBC News and according to a spokesman, refuses to do business in France until he gets a proper apology.

We are starting to run out of Russian billionaires to pin this on. Well, that's not entirely true, there is still a long list but hopefully someone will own up to the $750 million purchase pretty soon. You can't keep a secret that big for too long.

The mysterious billionaire who just bought the world's most expensive house - the $750 million Villa Leopolda (above) on the French Riviera - is none other than controversial Russian precious metals mogul Mikhail Prokhorov, the AFP reports. Luxist readers may remember Prokhorov as the over-the-top tycoon who announced plans in April to spend $150 million launching a magazine for snobs in Russia, called simply Snob. Prokhorov is ranked as the 24th richest man in the world with a $22 billion fortune. Some earlier reports had erroneously identified the villa's buyer as Roman Abramovich. Last year Prokhorov was briefly detained during an investigation into a suspected prostitution ring at the ritzy ski resort he frequents in the French Alps.