A mansion in London's posh Belgrave Square has hit the market for £100 million, or about $150 million, tying it with Candy Spelling's The Manor in Beverly Hills for the title of the world's most expensive estate (in terms of current listings). The six-floor, 21,000-sq.-ft. white-stucco-fronted building has 12 bedrooms, 20-ft. ceilings, a basement swimming pool, gym, media room, and every imaginable luxury fitting. The property has been gutted and revamped by Lebanese developer Musa Salem, the London Times reports.

Across the Square another house has recently come on the market for £80 million, or about $120 million. The eight-bedroom, 20,000-sq.-ft. house is being sold by Saudi Arabia's Juffali family, following the death of its owner. Belgrave Square is also home to Russian oligarch Oleg Deripaska and Sheikh Mohammed bin Rashid Al-Maktoum, the Emir of Dubai, as well as several embassies. The Square was built for the 2nd Earl Grosvenor, later the 1st Marquess of Westminster, in the 1820s and is one of the grandest in London.

Formerly Russia's richest man, Oleg Deripaska, shown above with Vladimir Putin, is now a billionaire in need of a little help. The St. Petersburg Times reports that Deripaska is asking banks to freeze loans that are set to come due for his company, aluminum producer RusAl. The company currently owes about $7 billion to foreign banks out of a total $16.3 billion of debt. The price of aluminum has continued to drop since last year and global stockpiles are high. The article quotes Deripaska as saying that he knows he can no longer get additional money from foreign banks and that Russia's government won't be able to supply much aid since it is consumed with social issues. He has asked for the government to help stimulate demand for aluminum and help producers compete on price because he feels that rivals are taking advantage during the crisis.

It's been quite a wild ride for Deripaska lately. He slipped onto our radar last August with the rumors that he might be interested in buying Hummer from GM. My colleague Jared Paul Stern also reported that Deripaska had paid singer Rhianna $500,000 for a private 40 minute performance for his friends on New Year's Eve 2007. Deripaska lost more than $35 billion over the past year and is now Russia's eighth richest man. His company, RusAl held on to a 25 percent stake in Norilsk Nickel after a $4.5 billion bailout loan from state development bank VEB but the stake's market value has fallen to about $2.1 billion down from $13 billion when RusAl bought the stock in April.

[via Wealth Bulletin]

Bad news for free-spending Russian billionaire and Luxist mascot Roman Abramovich: he lost a staggering $20 billion over the past few months as Russia's financial markets took a tumble. The figure was calculated "based on assets excluding property and cash," Bloomberg reports, and it means that Abramovich's net worth is now only $3.5 billion. He had previously been ranked as the 15th richest man in the world with a fortune of $23.5 billion.

Some other Russian oligarchs have fared pretty poorly as well. Russia's richest man - well, formerly anyway - Oleg Deripaska lost more than $16 billion, and Vladimir Lisin lost $22 billion. Overall, Russia's richest men have lost a combined total of $230 billion in five months, Bloomberg notes. No single man has suufered as much as Indian steel tycoon Lakshmi Mittal, who lost $28 billion as we reported earlier this week. Still, Abramovich's loss is likely to affect him more as he so obviously enjoyed spending his immense wealth. So - anyone want to buy a $350 million megayacht?

A group of billionaire investors including Oleg Deripaska (Russia's richest man) and LVMH chairman Bernard Arnault are backing a scheme to turn Tivat, a derelict port and ex-Yugoslav naval base in the former communist country of Montenegro, into the next playground for the megarich. The site's former naval dockyard fronting the Adriatic Sea will be converted into a lavish marina for superyachts, officially dubbed Porto Montenegro and biiled as "the Monaco of the Balkans," at a cost of around $350 million, the Times of London reports.

"The yachts are getting bigger and bigger," says Canadian mining magnate Peter Munk, who conceived of the project. "And people are complaining that they can't find proper berths for their boats. That's no problem in Tivat. It used to cater to warships." In addition to the great natural beauty of Montenegro, the development will feature moorings for up to 800 yachts as well as repair yards, hotels, restaurants, shops and possibly a casino. In addition, the Four Seasons is building its first Mediterranean resort there on the site of a former warehouse, slated to open in 2010.

Meanwhile, another oligarch, Luxist mascot Roman Abramovich, is said to be in talks to purchase an eight-mile strip of beach to build his own Montenegrin luxury resort, while Michael Douglas and Catherine Zeta-Jones and Venus and Serena Williams have recently been spotted house-hunting in the area, the paper reports. This is something of a throwback to the 1950s and 1960s, when stars like Elizabeth Taylor, Sophia Loren and Kirk Douglas holidayed on Montenegro's beautiful red-tiled resort island of Sveti Stefan (above). See the gallery for more.

For the very first time in the history of Russia, over 100 children are in line to inherit more than $1 billion each from their ultra-rich oligarch fathers. Russian business magazine Finans has found the number of likely legatees swelled to 112 this year, as compared with 70 last year, the London Telegraph reports.

At the top of the list are the two toddlers belonging to Russia's richest man, Oleg Deripaska, who stand to inherit as much as $20 billion each. The paper notes the list is not terribly scientific, however, as the rankings were arrived at merely by dividing each billionaire's fortune by the number of children he has, without regard to age, primogeniture or other mitigating factors.

Therefore, since Luxist mascot Roman Abramovich (right) has five children, his brood only clocks in at No. 34, with an expectation of $4.6 billion each. Elsewhere on the list, Lukoil owner Vagit Alekperov's son makes No. 2 with $13.5 billion coming to him, and steel tycoon Vladimir Lisin's three children rank at No. 14 with $7.4 billion each. See the gallery for some of Russia's richest dads.

Oleg Deripaska (right), 40, the richest man in Russia with a fortune of $28 billion and the 9th richest man in world (Luxist fave Roman Abramovich is #15), has reportedly held talks with General Motors about acquiring their beleaguered Hummer division.

As my colleague Deidre Woollard reported last month, Hummer is in financial trouble in the wake of the oil and gas price explosion, with sales of the SUV having tumbled some 40 percent through June. Ailing GM has announced plans to unload the brand, and Deripaska, whose company Russian Machines recently acquired a major stake in Canadian auto parts manufacturer Magna International, is a natural buyer.

In the wake of the reports, Russian Machines issued a statement saying it was "not strategically interested in such a deal", which sounds to us like a non-denial denial. We would hardly expect him to invite counter-offers by publicizing a planned acquisition before the deal is signed. This past New Year's Eve Deripaska paid Barbadian signer Rihanna $500,000 for a private 40 minute performance for his friends.