Paraphrasing

-While the Sears Tower is arguably the greatest achievement in skyscraper engineering so far, it's unlikely that architects and engineers have abandoned the quest for the world's tallest building. The question is: Just how high can a building go? Structural engineer William LeMessurier has designed a skyscraper nearly one-half mile high, twice as tall as the Sears Tower. And architect Robert Sobel claims that existing technology could produce a 500-story building. From Ron Bachman, "Reaching for the Sky." Dial (May 1990): 15-

Paraphrased :  Nowadays, the Sears (Willis) Tower is the highest exponent of skyscraper’s engineering. Nontheless, engineers won’t abandon the quest to build even taller skyscrapers. Several experts believe in the possibility that today’s technology is enough to produce very tall buildings, taller than the ones done before (Bachman 15).