A new bridge is being built in the Bay area of San Francisco California and Newbaybridge.org is a website that takes you on a journey from early 1900's to present day bridge construction.
This site has an amazing amount of information on bridge construction and also how to construct a bridge in an earthquake zone. With a tour of the history of the original Bay Bridge, photo galleries of the present build and interactive models makes this site a great classroom resource.
One of the stars of the site (from an educators point of view) is the classroom area called
Build your own bridge.
Note: The interactive "build your bridge" may load a bit slowly at the start....but it is worth the wait (or have it preloaded before class).