This passage is primarily designed to
a) encourage the study of architecture.
b) persuade readers to become architects.
c) teach about the history of skyscrapers.
d) describe the tallest buildings in the world.

1Humans have long competed to have the biggest and the best of everything. Therefore, it isn’t surprising that the race to have the tallest skyscraper is competitive and spirited. Since adventurous architects planned the first skyscrapers in the late 1800s, builders have been testing the limits of technology and physics with their buildings. The four tallest buildings in the world—sometimes called superscrapers—are higher than most builders would have thought imaginable. Even these huge buildings, however, will undoubtedly be eclipsed by larger structures in the future.  

Dubai  

2One of the greatest architectural achievements of all time is the Burj Dubai, which is located in Dubai, United Arab Emirates (UAE). Although the towering structure is still under construction, it has already past the height of the former tallest building in the world. The Taipei 101 in Taipei, Taiwan, held the title for about fours years before the Burj Dubai sprouted higher. Not only is the Burj Dubai currently the world’s tallest building, but also the world’s tallest freestanding structure. The CN Tower in Toronto, Canada, held that title until 2008, when the Burj Dubai eclipsed it. When finished, the Burj Dubai will stand over 160 stories high and will have taken over five years and tons of reinforced concrete, steel, and glass to complete. Upon completion, the building will house both residential and commercial spaces including business suites, fitness facilities, hotels, luxury pools and spas, and an observation platform. Because of its enormous size, the builders of Burj Dubai took care to make it resistant to the effects of winds and earthquakes. The building has a special design that will help prevent a catastrophe.  

Taipei 101  

3Before the Burj Dubai became the tallest building, the Taipei 101 in Taipei, Taiwan, was the tallest building in the world. The building gets its name from its 101 floors that tower above the ground. It also has five floors below the earth. Builders installed the fastest elevators in the world in the huge building. These speedy elevators can carry passengers from the first basement level to the eighty-ninth level in the only thirty-nine seconds! Taipei 101, which is also called the Taipei International Business Tower, houses many different facilities. A library, a five-floor shopping mall, fitness centers, restaurants, and communication hubs are among the many different facilities located inside the tower. Although the tower is equipped with the latest technology, it has many traditional Chinese elements. For example, the stacked sections of the building make the tower look like a bamboo shoot.  

Petronas Towers  

4The third and fourth highest buildings in the world are actually a tie. These two buildings are the Petronas Towers in Kuala Lumpur, Malaysia. The almost identical towers stand 1,483 feet high, including their 242-foot spires. The Sears Tower in Chicago, Illinois, actually has more stories than the towers, but the addition of the spires in 1998 pushed the towers above the height of the Sears Tower. The Petronas Towers were built to serve as the headquarters of Petronas—Malaysia’s national petroleum company. A two-story bridge connects the towers at their forty-first and forty-second floors. The bridge, called the skybridge, is a beautiful addition to the towering structures. The towers were the world's tallest buildings from 1998 to 2003, when builders finished Taipei 101.

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