Warren Buffett Omaha, Neb.
Net Worth: $37 billion
Rank: 2
The world's second-richest man still resides in the 6,000-square-foot, five-bedroom gray stucco home he bought in 1958 for $31,500. The 77-year-old keeps fit on his very own handball court. In 2007 an intruder armed with a fake gun tried to break into the modest, ungated property, but was thwarted by security.
Bill Gates Medina, Wash.
Net Worth: $40 billion
Rank: 1
Gates' 66,000-square-foot compound is built into a hillside on the edge of Lake Washington, near Seattle. Out-of-shape visitors can skip the 84-step hike to the ground floor and opt for an elevator ride instead. Among its enviable amenities: a 60-foot swimming pool with an underwater music system, a 2,500-square-foot gym and a 1,000-square-foot dining room, which seats 24.
Lakshmi MittalLondon, England
Net Worth: $19.3 billion
Rank: 8
In 2004, Mittal paid $128 million for this 12-bedroom townhouse in the luxury Kensington neighborhood called Billionaires' Row. Mittal's mansion has an indoor pool, Turkish baths and garage space for 20 cars. The super-home is embellished with marble taken from the same quarry that supplied the Taj Mahal.
Larry Ellison Woodside, Calif.
Net Worth: $22.5 billion
Rank: 4
Over the last few years, the Oracle co-founder has kept jaws a-dropping by spending $200 million by some estimates on near a dozen properties in Malibu, including five homes that in aggregate would create a custom compound. His 23-acre estate in Woodside, pictured here, is reminiscent of a 16th-century imperial Japanese palace and reportedly cost upward of $100 million to build.
Michael Dell Austin, Texas
Net Worth: $12.3 billion
Rank: 25
Built in 1997, Dell's 33,000-square-foot manse sits on a 20-acre spread a stone's throw from where he founded his eponymous computer company. It is known locally as "the castle" thanks to its high walls and tight security.
James Packer Sydney, Australia
Net Worth: $2.5 billion
Rank: 261
The young media heir was raised at the Packer family compound in the tony Bellevue Hill suburb of Sydney. The centerpiece of the five-property spread, which stretches nearly three acres, is Cairnton, the main house, bought by Packer's grandfather in 1935.
Steve Jobs Woodside, Calif.
Net Worth: $3.4 billion
Rank: 178
In 2007 preservationists in Woodside, Calif., successfully quashed the tech superstar's plans to demolish the Jackling House, his 30-room historic, though dilapidated Spanish Colonial revival-style home set on six acres. Jobs had hoped to raze the 17,000-square-foot mansion and build smaller, newer digs. No matter. Word is he and his family haven't lived in the house for years.
Lev Leviev London, England
Net Worth: $1.5 billion
Rank: 468
In 2008 the world's largest diamond cutter decamped from Israel to the posh London suburb of Hampstead. His new $65 million home, called the Palladio, is an extravagant 17,000-square-foot, seven-bedroom estate replete with in-house nightclub and gold-plated indoor pool. Neighbors include musicians Ringo Starr and Maurice Gibb.
Ralph LaurenMontauk, N.Y.
Net Worth: $2.8 billion
Rank: 224
America's original fashion mogul bought this stone and wood beach house, situated on five-and-a-half acres, in 1981. The cozy home, which boasts a clay tennis court, once belonged to John Lennon and Yoko Ono.