For a short time (till May 2009 I believe) the Computer History
Museum in Mountain View, California, has a Babbage Difference Engine
on display in their lobby. I was lucky to have the time to visit
and take photographs of this incredible machine.
The full story can be found here:
http://www.computerhistory.org/babbage/
The short summary is that Charles Babbage designed the first
automatic computing device in 1849, but it was not built until
2005. The London Science Museum built two copies. The first is
to be kept in their Museum for permanent display. However the
second one stopped in Mountain View for the only public display
in the U.S. before
disappearing into Nathan Myrvold's private collection.
These pictures were taken with a Canon EOS 30D camera
and Canon EF-S 17-85mm f/4-f/5.6 IS USM lens. Enjoy!