The Petronas Twin Towers remain the tallest twin buildings in the world

Designed by Argentine-American architect César Pelli, the Petronas Towers were completed in 1998 after a seven year build and became the tallest buildings in the world on the date of completion.[6] They were built on the site of Kuala Lumpur's race track.[7] Because of the depth of the bedrock, the buildings were built on the world's deepest foundations.[8] The 120-meter foundations were built within 12 months by Bachy Soletanche, and required massive amounts of concrete.[9]

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.[10] 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).[11]

Due to a lack of steel and the huge cost of importing steel, the towers were constructed on a cheaper radical design of super high-strength reinforced concrete.[12] High-strength concrete is a material familiar to Asian contractors and twice as effective as steel in sway reduction; however, it makes the building twice as heavy on its foundation than a comparable steel building. Supported by 23-by-23 meter concrete cores[13] and an outer ring of widely spaced super columns, the towers use a sophisticated structural system that accommodates its slender profile and provides 560,000 square metres of column-free office space.[14] Below the twin towers is Suria KLCC, a shopping mall, and Dewan Filharmonik Petronas, the home of the Malaysian Philharmonic Orchestra.

Other buildings have used spires to increase their height but have always been taller overall to the pinnacle when trying to claim the title. In the aftermath of the controversy, the rules governing official titles were partially overhauled, and a number of buildings re-classified structural antenna as architectural details to boost their height rating (even though nothing was actually done to the building).