More formerly called Subterranean Developments, construction projects that lead to what are colloquially and often derisively

called iceberg homes involve building substantial basements underneath comparably small,

above-ground real estate, usually because there are rules on the books that make it either

expensive and tedious or illegal to build upward or outward. So if you're a very wealthy person

who buys a nice house, maybe an older three-bedroom place in a nice neighborhood in a dense city,

that house unto itself might be stellar for most people's needs, but you're a very wealthy person

and you want more bedrooms, maybe a pool, maybe a bowling alley, and lounge,

none of which will fit in the square footage you own in above-ground property. Local laws won't

let you build up, as many such laws either have caps on the number of stories you can have on

your home to avoid messing with the view or to prevent property developers from swooping in, scooping up homes

and converting them into multi-story apartments or condos. And you can't build outward horizontally

because it's a dense area in a city and there might be laws about buying up neighboring properties

and combining them as well. So you start digging instead. You expand an existing basement or drill an entirely new one,

and you go down and down and down and in some cases out as well, expanding your underground

real estate to the very edges of your legal ownership beyond your home's walls, bumping right up

against the on-paper lines, dividing your yard from your neighbors.

This is not a theoretical, maybe someone will do this at some point concept, and it's not unusual.

It's so common, in fact, that the local legal and regulatory establishments in parts of London

have had to produce and publish separate guideline documents exclusively related to subterranean development efforts because so many of their residents were either engaging in the practice already or trying to figure out how to legally engage in the practice in the next several years.

And the below ground spaces these homeowners have been building are substantial.

Some homes go down four stories, creating an inverted medium-rise building underneath an above-ground, two-story mansion.

Some homes have basements jam-packed with pools, gyms, movie theaters, ballrooms, servants' quarters, and just about anything

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