The first two bridge pictures on this page are the old Colorado Street Bridge in Pasadena, Caliornia.  I love this bridge because it is beautifully designed and was made the old fashioned way where they made molds/forms from wood and poured in the concrete to form the bridge.  If you look closely at these two pics, you can see the ridges in the cement that come from the old wooden forms which are removed after the cement dries.  If you do a Google search for "Colorado Street Bridge" and then click on "images", you'll see it in total. 

The next three photos are from a massive ten lane freeway bridge that sits next to the old Colorado Street Bridge.  This bridge goes virtually unnoticed when you drive over it on the freeway but the underlying superstructure is very impressive and massive.  I love the sculptural curves of this bridge that almost no one sees.  It can only be viewed by taking a small side road.

The last picture on this page is an underground street in downtown Los Angeles.  The daylight shining down from above gives it an ethereal look.

Visit the link below to read the history of the Colorado Street Bridge.

http://en.wikipedia.org/wiki/Colorado_Street_Bridge_(Pasadena,_California)