The Yangtze, often called simply the Chang Jiang (Long River) in China, runs for 6,240km from the Tibetan Plateau to the Pacific Ocean, making it the world's third longest river.
Navigable for 2,400km, it is also China's spine, the central thread in its nervous system. Around 350 million people live in Yangtze Valley, whether crowded into great cities such as Chongqing and Shanghai or perched on precipitous hillsides.
A kind of modernity forced its way along the river from the mid-19th century onwards, as the western powers, seeing the Yangtze as a highway into the vast markets of China's interior, seized control of 10 Treaty Ports along its banks. Until the establishment of the People's Republic in 1949, British and American ships dominated the waterway, with the Royal Navy's gunboat diplomacy ending only in April of that year when two of its ships were attacked by Communist forces.
The Yangtze's political, economic and geographical centrality made the idea of taming and controlling it into something of an obsession for China's new rulers. Mao Zedong swam across the river three times in 1956 to impress on the watching crowds his virility and his mastery. The following year, the communist government completed the first bridge across the Yangtze, at Wuhan. But the ultimate symbol of mastery over the river would be the Three Gorges Dam, long dreamed-of by previous Chinese leaders, but never seriously attempted.
Though it had a special appeal for the communists, the dam symbolised a broader search for modernity. It was first mooted by the great nationalist leader Sun Yat Sen in 1919, and it was an American government engineer, JL Savage, who, in 1944, presented the first practical plan. But the project was fiercely controversial, even within the Communist Party, with critics keeping up vociferous opposition from the late 1950s until 1992, when it was finally approved by the National People's Congress. Even then, the congress, which usually reaches a consensus before a formal vote, was clearly divided, with 1,767 delegates voting in favour, but 846 voting against or abstaining.
The project - consisting of a dam that is 2,309m wide and 185m high; 26,700,000kw power generators that line the two banks of the river; and the world's largest ship lock - began in 1993 and is expected to finish in 2008, a year ahead of schedule. The budget is more than €20 billion, though the current estimate is that the cost will be just €18 billion.