Petronas Twin Towers, Kuala Lumpur, Malaysia

The Petronas Twin Towers were the tallest buildings in the world until Taipei 101 took over the record. The Petronas Twin Towers remain the tallest twin buildings in the world. 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 by Bachy Soletanche, and required massive amounts of concrete.

The 88-floor towers are constructed largely of reinforced concrete, with a steel and glass facade designed to resemble motifs found in Islamic art, a reflection of Malaysia's Muslim religion. Another Islamic influence on the design is that the cross-section of the towers is based on a Rub el Hizb (albeit with circular sectors added to meet office space requirements).

he towers feature a skybridge between the two towers on 41st and 42nd floors, which is the highest 2-story bridge in the world. The bridge is 170m above the ground and 58 m long, weighing 750 tons. 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 free passes (limited to 1700 people per day) must be obtained on a first-come, first-served basis. Visitors are only allowed on the 41st floor as the 42nd floor can only be used by the tenants of the building.

Architect: César Pelli