One of the most competitive contests in construction, the "world's tallest" title passes regularly from skyscraper to skyscraper. Architects and engineers heartily embrace the challenges of building higher, and corporations and cities are always attracted to the glory of towering over the competition. So, which building is the highest?

There is some debate over which building holds the record. Not everybody agrees on which structures should be considered. Traditionally, the architectural community defines a building as an enclosed structure built primarily for occupancy. This excludes a lot of extremely tall freestanding structures, such as Toronto's 1,815-foot (553-m) CN Tower, from the running.

Even within "traditional buildings" there is some controversy. Conventionally, decorative structures count toward height, but antennas do not, giving the Petronas Towers in Malaysia, built in 1997, at 1,483 feet (452 m) each, the official lead. However, if rooftop antennas were included in the total height measure, the Sears Tower in Chicago would take first prize at 1,730 feet (527 m). Many Chicagoans also point out that their Sears Tower has the highest occupied floor, at 1,431 feet (436 m), and the highest traditional roof at 1,454 feet (443 m).

Top Ten (July 2001)
1. Petronas Towers (Kuala Lumpur, Malaysia) - 1,483 ft (452 m)
2. Sears Tower (Chicago, USA) - 1,454 ft (443 m)
3. Jin Mao Building (Shanghai, China) - 1,379 ft (420 m)
4. Empire State Building (New York City, USA) - 1,250 ft (381 m)
5. Central Plaza (Hong Kong, China) - 1,227 ft (374 m)
6. Bank of China (Hong Kong, China) - 1,209 ft (369 m)
7. Emirates Towers (Dubai, UAE) - 1,149 ft (350 m)
8. The Centre (Hong Kong, China) - 1,149 ft (350 m)
8. T&C Tower (Kaohsiung, Taiwan) - 1,140 ft (347 m)
10. Amoco Building (Chicago, USA) - 1,136 ft (344 m)

By all accounts, the skyscraper race is far from over. There are more than 50 proposed buildings that would break the current record. The 1,550-foot (472-m) 7 South Dearborn building, nearing completion in Chicago, will squeak by the 1,483-foot Petronas Towers. China is working on the Shanghai World Financial Center, which it says will be something more than 1,500 feet (457 m). The proposed pyramid-shaped World Center for Vedic Learning in Jabalpur, India, will tower over the city at 2,222 feet (677 m). One of the most ambitious projects, Hong Kong's 4,029-foot (1,228-m) Bionic Tower, will include 300 stories.

The 7 South Dearborn building and several other relatively conservative structures are already in construction. The more ambitious buildings in the group are only theoretical at this time. Are they possible? According to some engineering experts, the real limitation is money, not technology. Super-tall buildings require extremely sturdy materials and deep, fortified bases. Construction crews need elaborate cranes and pumping systems to get materials and concrete up to the top levels. All told, putting one of these buildings up could easily cost tens of billions of dollars.

Experts are divided about how high we can really go in the near future. Some say we could build a mile-high (5,280 ft / 1,609 m) building with existing technology, while others say we would need to develop lighter, stronger materials, faster elevators and advanced sway dampers before these buildings were feasible. Speaking only hypothetically, most engineers won't impose an upper limit. Future technology advances could conceivably lead to building that are sky-high cities, many experts say, housing a million people or more.

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