Burj Khalifa

At 828 m, the tallest building in the world, soaring above downtown Dubai.

While it was being built, the tower was called Burj Dubai, meaning "Dubai Tower". At its opening it was renamed after Sheikh Khalifa bin Zayed Al Nahyan, then president of the UAE, whose government had helped Dubai with money during a world financial crisis. With 163 floors, it also holds the record for the most floors in any building, and it helped make Dubai known all over the world.

How it was built

Work began in January 2004, and the outside of the tower was finished in October 2009. The main structure is reinforced concrete, which means concrete strengthened with steel bars, and about 330,000 cubic metres of it went into the building. Because summer temperatures in Dubai can reach 50 °C, builders added ice to the concrete in summer and poured it at night, so it would harden slowly and evenly without cracking. The tower stands on 192 concrete piles, long pillars buried more than 50 metres into the ground. The main builder was the South Korean company Samsung C&T, working with a Belgian and a local company.

Why it has that shape

The tower was designed by the American firm Skidmore, Owings & Merrill, with Adrian Smith as chief architect. Seen from above, it has three wings around a six-sided central core, a bit like the letter Y. The designers took ideas from a desert flower called Hymenocallis, also known as the spider lily, and from patterns in Islamic architecture. As the tower rises, its wings step inward 27 times in a spiral. This makes it narrower toward the top and breaks up the swirling winds that could make it shake. The very top is a steel spire more than 200 metres tall.

Visiting today

Visitors ride some of the fastest double-deck lifts in the world, moving at up to 10 metres per second, to observation decks on the 124th and 148th floors, and there is a lounge even higher, at 585 metres. Around the tower is a large park with pools and fountains. Living high up has a surprising side effect: people on the upper floors see the sun for a few minutes after it has set on the ground, so during Ramadan, residents above the 80th floor wait about two extra minutes to break their fast.

On the globe

The model shows the slim, silvery tower in Dubai, stepping inward as it rises to a needle-like spire. Look how far it rises above the buildings of downtown Dubai.