Tobiko, 35, moved into a new one-storey home this year -- made of tree branches tied with sisal and coated with about six inches (15 cms) of cow dung and mud.

Here in Amboseli, lions and elephants are residents' most pressing concerns, not road accidents or muggers.

"People go and live in the towns but most come back because they feel there's no culture there," Tobiko said.

He may be right but for now, more and more people are moving to the world's cities and this population shift promises to usher in an urban age -- 6,000 years after the first cities emerged in Mesopotamia and the Indus Valley.

According to UN data, the world's urban population is poised to surpass the rural total for the first time in history.

One UN estimate says Aug 16, 2008 will be the day the shift will happen, with the urban population expected to overtake the 3,349,383,005 estimated rural total. Officials admit that is based on projections and incomplete censuses.

By 2030, two-thirds of humanity will live in cities. New buildings are likely to dwarf what are now the tallest icons of urban life -- the Taipei 101 building at 509 metres (1,670 ft) or the 452-metre (1,483 ft) Petronas Towers in Kuala Lumpur.

By that year, more than half of all Africans will live in cities, making up a larger population than the whole of Europe.

The date of the overall shift may still be under debate but experts say the change is inevitable.

"We live in an age of unprecedented, rapid, irreversible urbanisation," said Anna Tibaijuka, head of the UN Human Settlements Programme UN-HABITAT. "The cities growing fastest are those of the developing world, and the fastest-growing neighbourhoods are the slums."

One billion people -- a sixth of humanity -- live in slums.

MEGA OR HYPER

This population shift will lead to a new kind of city -- "mega cities" with more than 10 million people will soon be eclipsed by "hyper cities" with more than 20 million.

So far, only Tokyo qualifies as a "hyper city" but the greater city areas of Mumbai, Lagos, Dhaka and Sao Paulo will also surpass 20 million by 2015, according to UN projections.

Urban life offers everything from restaurants, bars, Internet cafes, cinemas, nightclubs, museums and theatres. Some people move to cities to experience living in a cultural melting pot, or in places seen as centres of power and innovation.

At the other end of the scale, many poorer people move to cities in search of work. Those who are unsuccessful can easily slip into a kind of city underworld, living hand-to-mouth in dangerous slums, far from family support.

But in wealthier lands, some find the opportunities offered by cities outweigh problems such as cramped spaces, higher costs, long commutes and often more crime and pollution.

"I like it here," said Elisabeth Andvig, 20, who lives in a an apartment by the fjord in Oslo, Norway's capital. In a German survey this year, the Aker Brygge district where she lives was named the urban area with the highest standard of living in Europe.

"You can just go out the door and (you) are in the middle of the city with access to shops and all kinds of services. And at the same time you live by the sea," she said.

Urbanisation is often credited with bringing better health, literacy and wealth. But people who live in slums suffer as much as the rural poor, according to a UN study.

In Brazil, malnutrition among children stands at 19 percent in slums against 5 percent in non-slum residential areas.