The opera house was nominated by some of the more than 19 million voters who have so far taken part in the campaign. After television documentaries featuring each of the sites, and further public voting, the winners will be announced on New Year's Day 2007.
Construction on the house began in 1959. Danish architect Jorn Utzon designed the famous roof, which is reminiscent of a ship at full sail. The project was beset with financial, engineering and bureaucratic difficulties, however, and Utzon resigned in 1966. The building was eventually completed in 1973; recently, Utzon agreed to help renovate the interior and other aspects of the building to bring it into line with his original vision.
Sydney's landmark faces competition from Rome's Collosseum, Jordan's Petra, the temple of Machu Picchu in Peru, and Britain's Stonehenge, as well as contemporary candidates such as New York's Statue of Liberty.
The original Seven Wonders of the World were selected by a Greek philosopher over 2,000 years ago and are due for an update. Original wonders such as the Colossus of Rhodes and the Hanging Gardens of Babylon no longer exist, although the Great Pyramid of Giza has proven more resilient, and made it onto the new list.
The New Seven Wonders Foundation was founded in 2000 by Swiss entrepreneur Bernard Weber. Half of the profits from the project will be channeled towards restoration and preservation work, including restoring the giant Bamiyan Buddhas destroyed by the Taliban in Afghanistan.