Last month, in successive weeks, I found myself on the Great Wall and the Great Dam. These are the two immense icons of China today, monuments to national pride and self-sufficiency. Some detect a newer wall still: the great firewall on the internet, keeping foreign ideas at bay. The Great Wall proved a beautiful fiasco, crossed by Manchu and Mongol invaders from the north, ending up as a crumbling relic of dynastic decay until inadvertently rescued by Chairman Mao's cultural revolution. The Three Gorges Dam, easily the world's largest, which will come into full operation in 2009, has yet to be tested.
It may turn China into an invincible colossus, with hydroelectric power generated from 26 turbines, and strategies for water conservation and flood control. It may, however, condemn it to irreparable environmental damage, quite apart from displacing 1.3 million people to faceless, liftless tower blocks in Chongqing, far from their rural homes, and destroying archaeological sites. The Yangtze is grubby; the dam could turn it in-to a putrid sewer. China's air is polluted: clouds of smog hang over Beijing and Xi'an, clogged by gridlocked cars. Wildlife is threatened: I saw remarkably few birds on my visit.
China has suffered from foreign intervention: the British burned down the imperial Summer Palace twice (1860 and 1900). But the unseen invasion from the atmosphere is much worse.
It is breathtaking to see the coexistence of tradition with revolutionary novelty all over China. The economy is expected to grow 10 per cent this year. The rate of construction is extraordinary. It is a land with a skyline of cranes: close to my 60-storey Shanghai hotel, 15 other monoliths were rising fast. This also entails relocation on a huge scale, such as moving the Beijing power station (coal-fired) out of the city by the 2008 Olympics. It is an empire of IT (carefully purged, as in the state-prompted censorship by Google), and yet, for the workers, morning begins with public exercises - balletic t'ai chi, of course, as well as ballroom dancing, ball games, and full-throated people's choirs to rejoice any Welsh heart. There was also synchronised rubbing of the back, the one physical exercise with which I identified.
The old is juxtaposed most spectacularly with the new in Shanghai, which blends the philosophic/aesthetic delicacy of city parks with skyscrapers, in a non-polluted atmosphere. The city is a joy for architectural enthusiasts, with its old neighbourhoods still visible alongside art-deco masterpieces in the one-time French Concession, riverside British classical and baroque buildings on the Bund, and the city's brilliant modern commercial real estate, so different from the incoherence of Canary Wharf. Shanghai glows with renewal after centuries of Chinese imperial decay and European imperialist exploitation.
Old and new merge more bizarrely on the Lijiang River down from Guilin, where the timeless idyll of fishermen against a lunar backdrop of limestone hills is challenged by a convoy of pleasure steamers proceeding downstream like some latter-day Armada.
China demonstrates the civilising impulses of community. It has the world's largest popu lation, yet no one ever bumps into you. The citizens walk slowly, with implied respect for others, whereas walking down the main streets in London involves, to use rugby parlance, a non-stop ruck and maul. There are few beggars here compared to Egypt or India. Cities are litter-free; in Beijing the vast expanse of Tiananmen Square is spotless (though not improved by the Chinese male penchant for full-throated spitting).
There are other benefits. Chinese women have made progress professionally, though most are still in thrall to old ideas about family, marriage and sexual propriety. Minorities, such as Tibet ans or Muslims, are treated better than many immigrants elsewhere; they can have larger families than the one officially permitted child.
Religious freedom is also emerging. In Shanghai, I found the Buddhist Jade Temple crammed with worshippers communicating with their ancestors on the day of the full moon. After prayers, they could recover their emotional balance in the temple's tea house, with ten different, no doubt equally therapeutic, blends of tea.
But while social freedom is growing fast, political freedom clearly is not. There is a systematic crushing of dissent. Past events in Tiananmen Square remain buried. Young people are alive to the contradictions of their state-controlled yet open-market consumer society, but puzzled by them. The ones I met were less at home with criticism of Tony Blair ("But he is your leader!") than with images of Margaret Thatcher, a respected commandant whose photograph appeared in restaurants next to those of such icons as Marlene Dietrich in The Blue Angel. And critics of the dam, for example, face oblivion - even execution.
A cult of retribution survives from 209BC. The now 7,000 terracotta warriors near Xi'an were all murdered by the first Qin emperor lest they betray the whereabouts of his tomb. Reform may be coming, however. Chinese civil servants visiting Oxford study the decentralisation of power. It is reassuring, too, that Sun Yat-sen's old house in Shanghai is a public shrine: republican China's founding father was a great democrat.
China has long been instinctively suspicious of "foreigners" - violently so during the Boxer Rebellion or in resistance to the US puppet regime of Chiang Kai-shek. And yet things could change. One young man said proudly that he had been abroad. He actually meant Hong Kong, still only part Chinese, with its separate currency and the need for visas to enter. Even so, Hong Kong's air of openness has some liberating effect. Millions of tourists pouring in after the Beijing Olympics might also encourage curiosity, even dissent.
In any case, maybe we exaggerate the historic difference of the Chinese. As my tour group gazed at a rickety religious monument in Suzhou, our young guide remarked, "Well, you have your leaning Pagoda of Pisa."