It's a big house.

Originally it was planned to have 45 stories, but the Ambanis decided they wanted more headroom. So, when completed in early 2009, the house will stand 27 stories covering 400,000 square feet. No zoning (or neighbor) problems; it's in the business district. The cost, originally set at $1 billion, is approaching $2 billion. Ambani, head of petrochemicals giant Reliance Industries, can afford it. FORBES ranks him the fifth-richest man in the world, at $43 billion.

The home's amenities include: separate gym for each family member, six stories of parking, four stories of open-air gardens, a ballroom covered with crystal chandeliers, a 65-seat theater, a spa, a swimming pool and an ice room. The ice room has you sitting while snow drifts onto your head, a nice way to escape from the Mumbai heat. Good luck picking out a housewarming gift.

So why did the Ambanis decide to go so big? Turns out the ultrarich aren't so different from the rest of us. They were living in a 22-story building, and it was time to upgrade. With the bigger residence they might be able to entice their two sons to move back after they finish college.

Visit forbes.com/ambanihouse for more information on the design and layout of the house.

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