Tổng hợp Đọc hiểu lớp 7 - Đề 21

Skyscrapers, Made in America

Skyscrapers were invented in the United States. Two new technological developments made very tall buildings possible in the late 1800s. One development was the mechanical elevator. It meant that people would not have to climb many steps to reach the upper floors of tall buildings. It saved time and effort. The second was good quality steel that could carry the heavy load of a tall structure. These two developments helped make the skyscraper possible. Many experts consider the Home Insurance Building in Chicago, Illinois to be the first skyscraper. It was completed in 1885 and later increased to a height of 55 meters. Today, this would not be considered tall. But at the time, this height was striking. What was different about the Home Insurance Building was its structure. It was built using a steel frame. This frame carried the weight of the building rather than the walls. The method was known as “skeleton construction” at the time. Before this technology, a tall building required thick stone walls to support its weight. Thick walls are extremely heavy and take up a big area that could be used for floor space or windows. William Jenney was the engineer who helped build the Home Insurance Building. He understood the possibilities that steel frames could offer. Some people consider him the father of the skyscraper. Soon after the building was finished, builders in Chicago and New York City began copying and improving on the idea of building upwards. Builders in these cities and others would also begin competing for the title of “tallest building.” Popular tall buildings The Empire State building in New York City was completed in 1931. It was the tallest building in the world for more than 40 years. It is still one of the most popular. Millions of visitors have seen New York from observation areas in this building. Chicago became home to the world’s tallest building in 1973 when the Sears Tower was completed. It is 442 meters tall. The Sears Tower, which is now called Willis Tower, was the tallest building in the world for 23 years. Then, in 1996, two taller buildings were completed. They are the Petronas Towers in Kuala Lumpur, Malaysia. They are about 452 meters tall. Who decides on the tallest buildings?