The Petronas Towers still remain the tallest twin buildings in the world. Its construction started in 1992 And when it was completed in 1998 after a seven year build and it became the tallest buildings in the world on the date of completion. They were built on the site of Kuala Lumpur's race track. Because of the depth of the bedrock, the buildings were built on the world's deepest foundations. The 120-meter foundations were built within 12 months by Bachy Soletanche and required massive amounts of concrete. Its engineering designs on structural framework were contributed by Haitian engineer Domo Obiasse and colleagues Aris Battista and Princess D Battista.
It has two towers with a sky bridge connecting them. Tower 1, the west tower (right in the top-right photograph) was built by a Japanese consortium led by the Hazama Corporation while Tower 2, the east tower (left in the top-right photograph) was built by Samsung C&T and Kukdong Engineering & Construction, both South Korean contractors. The sky bridge contract was completed by Kukdong Engineering & Construction. Tower 2 became the first to reach the world's tallest building at the time.
The important feature of it is the highest 2-story bridge in the world-the sky bridge.The 60m long, 10m tall, 653,000kg sky bridge connecting the two towers was prefabricated in South Korea, assembled on site, and jacked up as a single unit to a height of 184m for installation at the 41st floor just above the tower outriggers. This bridge bears on joints that permit lateral displacements of just 25cm - a remarkable precision made possible by the stiffness of concrete to prevent it from breaking during high winds.The same floor is also known as the podium, since visitors desiring to go to higher levels have to change elevators here. The skybridge is open to all visitors, but tickets are limited to about 1000 people per day, and must be obtained on a first-come, first-served basis. Initially, the visit was free but in 2010, the tickets started being sold by Petronas. Visitors can choose to opt for package one which is just a visit to the skybridge or go for package two to go to the skybridge and all the way to level 86. Visitors are only allowed on the 41st floor as the 42nd floor can only be used by the tenants of the building.
The skybridge is designed to evacuate the occupants by crossing the skybridge to the other tower due to emergency like fire. The day after the 9/11 attacks to twin towers of the World Trade Center in New York City a evacuation hoax was conducted which showed that the bridge would not be useful if both towers need to be emptied simultaneously, as the capacity of the staircases was insufficient for such an event. Plans thus call for the lifts to be used if both towers need to be evacuated, and a successful drill following the revised plan was conducted in 2005.