The super-rich are maximizing property value in the heart of London as never before. But they're not building up, they're digging down, creating mega-basements or 'iceberg homes' - nicknamed because there's more square footage under the ground than above. Over the last ten years an estimated 2000 new basements have been dug in central London. Into these multi-level subterranean structures owners are building anything from cinemas, swimming pools, beauty parlours,... see more