The nominated site covers four farming villages and 200 of the 1,833 watchtowers in Kaiping, a low-lying area at the junction of Xinhui, Taishan, Enping and Heshan counties. The towers were owned by people who left Kaiping between 1840 and the early 20th century to work goldmines and build railways in the US, Canada and other countries.

They sent money back to build the towers to house their families and protect them against floods and bandits. And when they returned, they also brought back the architectural styles they so admired.

As a result, the upper parts of many of the towers featured colonnades, terraces or overhangs. Many also had cannons and slit windows for security purposes. Some carried elaborate interior designs.

The application office has spent about HK$130 million since it started preparing in 2000. Conservation experts from Hong Kong, Macau, and other places were hired as consultants. Cables were laid underground and tall factory buildings were razed to allow for unobstructed views.

Selia Tan Jinhua, acting director of the Kaiping Diaolou Research Department, said Unesco assessment teams had offered their support in recent visits.

But to Ms Tan, the most important factor was the Kaiping villagers. 'They are the owners of this heritage,' she said. 'To succeed in this project, the very first thing we needed was their recognition.'

Her office held conservation workshops with the villagers. 'At first, they thought we were trying to take away their land and property. It took a few years to explain to them why we wanted the site inscribed.'

Tax incentives were given to businesses that were set up at the site. Locals were also trained as guides.

'We are very confident about this nomination,' Ms Tan said. 'The towers reflect the cultural and historical links between China and the rest of the world.'