The World's First Billion-Dollar Home

While visiting New York in 2005, Nita Ambani was in the spa at the Mandarin Oriental New York, overlooking Central Park. The contemporary Asian interiors struck her just so, and prompted her to inquire about the designer.

Nita Ambani was no ordinary tourist. She is married to Mukesh Ambani, head of Mumbai, India-based petrochemical giant Reliance Industries, and the fifth richest man in the world. ( Lakshmi Mittal, ranked fourth, is an Indian citizen, but a resident of the U.K.)

Forbes estimated Ambani's net worth at $43 billion in March. Reliance Industries was founded by Mukesh's father, Dhirubhai Ambani, in 1966, and is India's most valuable firm by market capitalization. The couple, who have three children, currently live in a 22-story Mumbai tower that the family has spent years remodeling to meet its needs.

Like many families with the means to do so, the Ambanis wanted to build a custom home. They consulted with architecture firms Perkins + Will and Hirsch Bedner Associates, the designers behind the Mandarin Oriental, based in Dallas and Los Angeles, respectively. Plans were then drawn up for what will be the world's largest and most expensive home: a 27-story skyscraper in downtown Mumbai with a cost nearing $2 billion, says Thomas Johnson, director of marketing at Hirsch Bedner Associates. The architects and designers are creating as they go, altering floor plans, design elements and concepts as the building is constructed.

The ghetto-fabulous full-monty in pictures, words, and video is at Forbes.com.