On Monday, Lee won the Grand National Party's ticket to the presidential vote, with polls showing he is the man to beat.

His most celebrated project as Seoul mayor was removing an elevated highway in the heart of the capital -- put up when he was a top executive at Hyundai Construction -- and restoring a stream that had been buried underneath it for about 50 years.

Built at a cost of some $400 million, the nearly 6-km (4-mile) long Cheonggyecheon stream park with restored ancient bridges and modern sculptures, has become one of the most popular spots in the country.

About 50 million people have visited the waterway since it opened in late 2005 in a country of some 49 million.

"Since I participated in the construction, I am well aware of the mistakes I made back then and I am trying to undo them," Lee said in an interview with Reuters in 2005.

Lee changed the map of Seoul when he became mayor in 2002 -- and the city has many more green spaces as a result.

Gone is a snarl of roads in front of City Hall. It has been replaced by a sprawling grass lawn used for public concerts, protest rallies and picnicking families.

Lee built a forest park along the Han River, the main waterway that runs through Seoul. He rearranged traffic patterns to set up bus lanes that moved commuters quickly and put in more sidewalks for pedestrians.

He earned points with the public by finishing several of these projects ahead of schedule and within budget estimates.

Critics say these projects were designed for short-term political gain and were not part of a comprehensive plan to transform Seoul's urban environment.

If elected president, Lee has promised to build what will likely be the biggest construction project in the history of the country -- a waterway from Seoul to the southern port of Busan.

He has said the canal will be an efficient way to move goods and should cut down on pollution because there will be fewer trucks on the road.