Work has begun on a high-speed rail link that will halve travelling time between the Chinese capital Beijing, and financial centre Shanghai.
Trains will travel at up to 350km/h (220mph) to make the journey between the two hubs in five hours.
The link will take five years to build and cost almost $32bn (£16bn), Chinese state media said.
Chinese Premier Wen Jiabao attended a ceremony in Beijing to mark the start of the construction.
According to Xinhua news agency, the rail link is the most expensive project that China has embarked on since 1949.
"The demand for both passenger and cargo transport along this line is huge," Xinhua quoted Vice Railway Minister Lu Chunfeng as saying.
"There's definitely a need for a modern, high-speed rail, built to a high standard and meant to have a large capacity," he said.
The project was originally intended to be ready in time for the Beijing Olympic Games, but has experienced severe delays.