London limits underground mansions

For years, the London rich have been on a subterranean building spree. Rather than building up, which often violated zoning rules, they built down, carving out underground swimming pools, cinemas, Ferrari museums and personal spas. Brits came to call them "iceberg homes" since most of their mass was hidden below the surface.

According to London's Telegraph, there were 450 applications for basement developments last year in Kensington and Chelsea—a ten-fold increase since 2001.

Skyline of London
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Now, the local government has had enough. After growing complaints about the noise, dirt and dust created by today's multimillionaire moles, the London borough of Kensington and Chelsea is placing restrictions on underground building. They can't be more than one-story deep, they can't be approved for certain historic buildings and they can't stretch too far under a garden.

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"This ruling is a victory not only for the council but also our residents who have been overwhelmingly supportive of what we have been trying to do," one council member told the Telegraph.

So far, the trend hasn't caught on as much in New York or other U.S. cities because there are fewer height restrictions. But some homes around L.A. are using underground development—including one 30,000 square-foot home that needed an additional 14,000 square-foot basement for the entertainment area.

To read the full Telegraph story, click here.