Business Notes REAL ESTATE

Ever since Chicago declared a ten-story building the world's first "skyscraper" in the 1880s, local developers have competed to see how high they could go. Since 1974, the Sears Tower (on the left in the model) has * ranked as the world's tallest building at 1,454 ft., but that title is about to be challenged by a planned $500 million tower only three blocks away from the current champ. Code-named Skyneedle, the 125-story building would soar to a height of nearly 2,000 ft. Rivals have criticized the proposal by developers Lee Miglin and Paul Beitler as too flashy and too skinny, with only one-third the floor space of the Sears Tower. But the Skyneedle builders hope to break ground in nine months and to finish in 1993.