For Mumbai's millionaires, the sky above is their only limit

Even India's richest man, Mukesh Ambani, could not find enough land in Mumbai to build a new home.

The tiny strip that constitutes Mumbai has so little land left it is close to imploding. Denied the pleasure of building a palatial estate, Mr Ambani had no choice but to go up and build a $US1 billion home on 27 floors.

Such is the land scarcity in Mumbai, where 14 million residents jostle for space (giving it the new tag ''Slumbai''), that even millionaires and billionaires struggle to find a home. Not that they are homeless, it's just that finding a home commensurate with their wealth and social status and located in the only place that counts - the centre of the city - is tough.

It has created a strange anomaly. When they travel abroad, the city's super rich enjoy the best money can buy. At home, the quality of living slips. With the demand surging for high-end homes, it's just as well that a residential tower called World One, a 117-storey colossus, is going up on 6.8 hectares of prime land. The developers, the Lodha Group, say World One, at more than 450 metres, will be the tallest residential tower in the world, taller than the Q1 building on the Gold Coast or the Jin Mao Tower in Shanghai. The 300 apartments and villas will range in price from $2 million to $12 million. More than 60 per cent are already sold.

The specifications of the $440 million complex, designed by New York architects Pei Cobb Freed & Partners, are striking: the larger homes have gigantic curved windows with 360-degree views of the city and the Arabian Sea; the interiors have been done by Giorgio Armani; there are private pools, gyms, clubhouse and a spa, spacious gardens and an open-air observatory.

This being India, where everyone is religious, each home will have a puja (prayer room). This being India, where no one likes to walk even a few metres, each floor will have its own parking space close to the homes. And this being India, the servants will have separate entrances and lifts to minimise inter-class mingling.

By home, people in Mumbai do not mean a house. The concept does not exist, owing to the land shortage. Even a millionaire's home will be an apartment. No builder will build a single home on a coveted plot; when real estate is among the most expensive in the world, he stands to make much more by building a tower.

But Mr Lodha and other developers are not just building opulent homes. They are altering the city's skyline. High-rise residential towers for the rich are mushrooming in the heart of the city - the districts where the famous cotton mills used to stand, dating back to the time when the city was known as the ''Manchester of the East'' because of its role in the economy of the British Raj.

After years of litigation, this land has been freed up for development. Builders are erecting shopping malls and dream homes for the rapidly growing number of Indian millionaires created by Asia's third-largest economy.

A report by the Swiss banking group Julius Baer last year predicted that India will have 403,000 dollar millionaires by 2015. And they will all need somewhere nice to live.