Chicago is a city of bridges. Pretty much every type of bridge there is, exists in Chicago. This is the bell on the southeast tender house on the Wells Street bridge, circa 1922.
The Wells Street bridge is a double decker bridge - the L runs on the upper deck, which is the red beam behind the bell. The bridges along the river go up at different times of the year to let the sailboats out on to the lake in the spring, back to dry dock in the fall - I believe the bridges are only tended now during these scheduled times.