Democrats swarmed when news broke last year that Mitt Romney had bought a $12 million mansion in La Jolla, California -- only to tear it down to build a house on the same land with four times the square footage. Romney bristled at the story, insisting that he was only doubling the size if you don't count the basement and garage.

Today's Wall Street Journal has a little more info on that basement in a trend piece on how ultra-wealthy home owners are building huge portions of their home below ground in order to appear less ostentatious from the outside. According to the plans for Romney's new home, the underground space will be 3,600 square foot. That's 600 square feet bigger than the entire mansion that the Romneys are replacing.