Despite being buried 32m beneath the English Channel the structure that links the UK to France beat the Sydney Opera House, the Panama Canal and the Empire State Building.

Fourth: The Empire State Building

Chief Executive of Eurotunnel George Christian Chazot said: "We are not the most beautiful project...we are the most secretive."

Four hundred engineers were asked what they considered to be the greatest achievement in their field, based on usefulness, economic impact, influence and innovations with new technology.

San Francisco's Golden Gate Bridge, built in 1937, came second, followed by an unusual choice for third - the 41,000 miles of the US Interstate Highway System as the largest public works project in history.

Sixth: The Sydney Opera House

Fourth was the Empire State Building in New York, followed by the Hoover Dam on the Colorado River, built in the late 1920s.

The 1914 Panama Canal - which cost the lives of more than 5,000 workers to construct - came sixth, the Sydney Opera House seventh and the Aswan Dam across the Nile in Egypt came eighth.

Ninth were the twin towers of the World Trade Centre, also in New York, which famously withstood a terrorist attempt to blow them up in 1993.