(Edit 8/13/2008: Via Xavier Thoughts. I had emailed myself the link and neglected to note where I had found it. I found it again today. Mea Culpa.)
(No video last week; I thought there was enough video already.)
World War I and World War II saw some extremely large guns that were moved by railroad. One of the largest was Dora:
Most historians think that the large railway guns were actually a drain on resources that could have been better employed elsewhere. They might be right, but it's still a pretty impressive sight.