Bridge Signs
- http://www.douglascoulter.com/BridgeSigns/
- Douglas Coulter's collection of bridge maker's plates from wrought iron bridges of Illinois. Also features photographs of covered and iron bridges, and bridge postcards.
China Bridge
- http://www.pbs.org/wgbh/nova/lostempires/china/
- Discover how China's Song dynasty during the eleventh and twelfth centuries used the high arch "rainbow bridge" to solve the problem of spanning a fast-moving river without impeding boat traffic. Nova online.