On Friday, July 23, hundreds of athletes will take to the 1,504 stairs of the Sydney Tower, the second-tallest building in Australia, to see how quickly they can reach the top.

No, they're not taking part in a reverse fire drill. The event, called the Sydney Tower Run-Up, is part of an emerging trend called vertical running or tower running. The setting? The stairwells of some of the world's tallest buildings, including the Taipei 101, the Empire State Building and the Sydney Tower.

The effort involved is grueling – the Taipei race, for example, means climbing 2,046 steps – but brief. In Sydney, the average finish time is 15 minutes, though whoever reaches the top the fastest will win an impressive $25,000 prize.

The views at the top of the buildings, however, are part of the appeal for all participants, along with the fitness benefits, including weight loss and increased strength and endurance. In addition, the races are a novel way to experience some of the world's most famous skyscrapers in a way most tourists couldn't even fathom.

In response to the growing popularity of the following, the International Skyrunning Federation, an Italy-based organization that oversees all types of high-altitude running events, has put together a global circuit featuring the world's most well-known skyscrapers. After Sydney, the circuit rounds out 2010 with the 712-step Torre de Collserola in Barcelona on October 15 and then Singapore's 779-step Swissotel the Stamford on November 16.

In addition, there are dozens of other events not on the circuit, including the CN Tower Climb in Toronto in October, which last year drew more than 12,000 people (and raised $1.7 million for charity), and Las Vegas's Scale the Strat, in the city's legendary Stratosphere Hotel. Smaller, community-based events are also becoming more popular. 

Ready to step to it? Visit www.verticalrunning.org or www.skyrunning.com.

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