Downtown Chicago
Chicago is an enormous city and it would take months to see all that it has to offer. Fortunately, there is enough to do in the downtown district that you may never even need to see anything else in the city. Be advised that Chicagoans do not refer to the city center as "Downtown". The area has been known as "the Loop" for several decades. When the city built the first elevated train tracks, the central commercial district was far too dense to allow for easy construction with the area, so a large circle of track was constructed around the tall buildings and narrow streets. The "Loop" has now outgrown the circle of track, but the name stuck.
Whatever you want to call it, there is plenty to see in the concrete canyons that are formed by some of the tallest buildings in the world. By all means, take a trip to the observation decks of either Sears Tower or the John Hancock Center. Depending on the day's visibility you will be able to see well beyond the city's limits to the suburbs and even adjoining states. State Street is Chicago's "Main Street" and has been closed off to traffic, creating for a pedestrian mall. However, serious shoppers head a few blocks to the east to the "Magnificent Mile" of Michigan Avenue with its trendy stores and designer shops. Back to the south lies Grant Park with its museums and the city's concert halls.