Not to change the subject, but I find that first photo to be incredibly interesting. My first love was locks and dams on the Green River near my home in the 1830's. That first photo shows the hull of a sternwheel packet steamer being built in the foreground. That is way cool.
jeez crazy bridge?
More info can be found here:
http://condrenrails.com/FSVB/Bridges/Iron-Mountain-Bridge.htm
This must have been an incredible structure. A multiple span Pegram truss is not something you see everyday.