Under the dazzling blue sky, the glass-walled skyscraper that is Capital Gate twinkles in the sunlight as people bustle in and out of the airy lobby.
Above them, just about visible, are the window cleaners -- suspended with ropes and harnesses, artfully polishing Capital Gate's 728 individually made glass panels, which are custom-designed to fit the building's unusual shape.
These so-called "cliffhangers" can be seen cleaning the diamond-shaped windowpanes every day, working their way around the building. A team of 12, they get through two rounds of Capital Gate every month.

Calling the 35-story Abu Dhabi building a skyscraper doesn't quite convey the essence of Capital Gate. The brief given to the engineers and architects was not to make the biggest or tallest building around, but to "challenge the rules of architecture and to build a structure that would put Abu Dhabi on the world map," says Ahmed Al Mansoori, a lead engineer for Capital Gate and Director of Engineering at Abu Dhabi National Exhibitions Company.
Nearly 10 years on, Capital Gate remains the world's "farthest man-made leaning building," according to Guinness World Records. It leans 18 degrees westward -- about five times the angle of Italy's Leaning Tower of Pisa -- and the top 17 floors "hang over the edge, putting thousands of tonnes of pressure on the core of the building," explains Al Mansoori.
"Nature wants it to collapse. Everything about the tower makes it want to fall over, but it has been designed to stop."

The gravitational pressure caused by the 18-degree incline is countered by the world's first "pre-cambered core," made up of 15,000 cubic meters of concrete reinforced with 10,000 tons of steel.
This core was deliberately built slightly off-center but straightened as the building rose, compressing the concrete and giving it strength, and moving it into vertical position as the weight of each floor was added.
Capital Gate is also kept upright by 490 piles which are drilled over 30 meters deep. "We created two sections of piling, one deeper than the other. Together they create competing forces that keep the building upright," says Al Mansoori.
The building is home to 15 floors of offices, four restaurants and bars, and a hotel, the Andaz Capital Gate. As well as nearly 200 rooms, the hotel has a deluxe Presidential Suite on the 33rd floor which straddles the dramatic 18-degree incline.
"Because of the shape of the building, every room in the hotel is different," says Andaz employee Julia Gimadyeva.