Shelling Out for Space in Mumbai.(Top Shelf)

Manhattan apartments cost on average $1,263 per square foot--less than in some parts of Mumbai.

By Sameer Reddy

Occasionally I amuse myself by perusing apartment listings online, fantasizing about the luxury pad I plan on purchasing as soon as I win the lottery. Though my only experience of the Upper East Side thus far consists of ambling along Fifth Avenue, it seems like the perfect place in which to live the well-manicured life that millions of dollars can buy. A recent Google search confirmed that one of Manhattan's most expensive apartments, the 1,269-square-meter penthouse of the Pierre Hotel, on which I've set my sights, is still available. It's been on the market since 2004; potential buyers apparently aren't finding it a steal at $70 million.

Perhaps the listing's agents, Brown Harris Stevens, should invest in a Mumbai office. After all, it's an Indian (steel magnate Lakshmi Mittal) who is in talks to purchase the world's most expensive house: a nearly $229 million mansion in London. And judging by the recent spate of high-profile, record-priced residential developments in Mumbai's toniest neighborhoods, there are plenty of others for whom the Pierre might make a cozy pied-a-terre.

Indeed, when it comes to real estate, Mumbai is India's Manhattan. Though thousands of kilometers apart, the two cities have similar characteristics: most important, both are financial and cultural centers built on islands, which means that they will one day run out of room. That point will likely come a lot sooner in Mumbai than in Manhattan, considering that it's already one of the most densely populated metropolises in the world. For its richest citizens, however, the space shortage is not much of a concern.

Just ask Mukesh Ambani. With an estimated net worth of $43 billion, the Reliance Industries chairman has embarked on construction of his own private Shangri-La in Mumbai, which, when completed, will be the world's most expensive private residence, rumored to cost nearly $2 billion. Ambani solved the issue of space by building up; his 27-floor steel-and-glass tower (with 60-story proportions), named Antilia, will have a movie theater, swimming pool, helipads, multilevel parking structure, hydroponic gardens, health club, snow room and more, all for a family of six. (To be fair, it will also serve various corporate functions.)

Ambani's favored 'hood, Cumballa Hill, has become Mumbai's Billionaire's Row, housing some of India's biggest names: industrialists Kumar Birla and Anil Agarwal, and media magnates the Sahu Jains, among others. Recently an unidentified buyer reportedly shelled out $100 million for a 1,000-square meter plot of land. Cumballa Hill is not the city's only posh address: neighboring Malabar Hill apartments can fetch up to ...