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A landmark Auckland public building and a railway line have been named as the country's most significant engineering feats.

That's according to two city leaders, who have challenged Auckland University's school of engineering survey on the most impressive achievements.

Last week, in a survey of 600 engineers, Manapouri Power Station, America's Cup yacht Black Magic and Auckland's Grafton Bridge came top.

But Auckland Mayor Dick Hubbard and Auckland Regional Council chairman Mike Lee beg to differ.

Mr Hubbard said: "In my opinion - and with a slight Auckland bias - the Auckland War Memorial Museum, which was a major achievement in 1925 and a city of 100,000 people."

Mr Lee took a wider view and cited the main trunk line through the North Island. "Because of the difficult terrain, its route through the King Country in the aftermath of the Maori land wars, and the available technology, this has to be the biggest, and most economically significant project in our history," he said.

Other civic representatives had alternatives.

Auckland City councillor Richard Simpson said the Parnell tunnel was the greatest.

The project was started in 1864 and finished in 1872.

"The tunnel is still there today but closed. I understand the original purpose was to build a railway to Drury for the purposes of fighting the Maori land wars, however during the construction there was a massive land slip from a stream - Waipapa - on the Parnell side of the tunnel on to the railway line," Mr Simpson said.

Funding disputes and a commission of inquiry into the slip also delayed completion. By the time it was completed the war in the Waikato was well and truly over, he said.

The tunnel enabled the first public railway line to be built and connected Auckland to the rest of New Zealand by rail. It became the gateway to Auckland for rail commuters, he said.

"This tunnel served as Auckland's gateway until the first day of World War I, when the current Parnell tunnel with its dual track took over the role," he said.

The little-known tunnel goes from the Domain to Newmarket Park and is now closed at both ends. It was chosen as an air raid shelter for Parnell residents during the World War II, he said.

Kaaren Goodall, executive director of the Committee for Auckland, cited the Rewarewa Bridge in New Lynn, designed by artist Virginia King.

"It hasn't got a single straight line in it," Ms Goodall said.