Chicago is located in the centre of the north American continent, is located in Illinois, is the largest city in the Midwestern United States, there are nearly 3 million people live in here. Chicago is America's third largest city, Chicago and its suburbs of the greater Chicago area had a population of more than 9.7 million, is second only to New York and Los Angeles third metropolitan area in the United States. Chicago is America's most important railway, aviation hub. Chicago is also a major U.S. financial, cultural, manufacturing industry, one of futures and commodities trading center. Since established in 1833, after more than one hundred years of development, gradually become one of the city has the world influence of Chicago. The lure of the National People's Congress will be called the most characteristic city in the United States, it will be the Midwest and the world legacy of culture and the food landscape be in harmony with the world. Norman Mailer wrote: "Chicago is a great American city, it may be of great American cities". Chicago also known as the world's top 10 richest city, Chicago skyline is one of the world's ten biggest skyline. Chicago is in 1871 after the reconstruction of the fire, skyscrapers in the area, second only to New York. Today's five tallest skyscrapers around the world have 3 in Chicago, the Sears tower in the centre of the city is the tallest building in America, 443 meters high.