Special passes were given out to hundreds of people, two hours before officials from Petronas, the national oil corporation, started ushering the visitors to the bridge that links the 1,483-foot landmarks, nearly halfway up on the 41st floor.
Security at the opening was also tight, both on the ground and the bridge, where Petronas officials escorted the visitors in groups of 20.
Tourists from as far as the United States but also from nearby Myanmar gripped metal railings and pressed their faces against glass walls, pointing at mosques, hotels and condominiums far down below.
"This is such a spectacular view," exclaimed Louise Rosen, a 42-year-old accountant from Trenton, New Jersey. "I'm really happy my husband and I came here for our summer vacation."
The Petronas Towers symbolize the pinnacle of Prime Minister Mahathir Mohamad's efforts to modernize Malaysia.
He officially inaugurated the buildings Aug. 17 last year, but only employees of the companies renting space the 88-story skyscrapers had access.
When the towers were completed in March 1996, they surpassed Chicago's Sears Tower, which, at 1,450 feet, had been the world's tallest building since 1973.
Mahathir has justified the $1 billion project, stating that it added pride of a small nation like Malaysia: "It is important because small people always like to appear tall."
The fame of the towers was extended when millions of people watched Catherine Zeta-Jones and Sean Connery scramble across the bridge in Hollywood's Entrapment.
Petronas estimated that nearly 800 people would visit the bridge by the end of the day. The rest of the Twin Towers remains off-limits to the public.
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