The "L" Train to Kimball – Viewed from the Corner of Wabash and Lake Streets, Chicago, Illinois, United States

The Chicago L is now 125 years old. This network of elevated trains and subways is how Chicagoans get around. But it’s also an iconic symbol of the city. In the late 19th and early 20th centuries, many American cities used elevated trains to transport their residents. In most cities, those elevated systems were eventually replaced by subways. While Chicago has two subway lines, the majority of its trains are either elevated or at grade (at ground level). Today, Chicago is the only city in the U.S. that still has elevated trains in its downtown area.