According to local lore, George Lucas was inspired to create the AT-AT walkers in "The Empire Strikes Back" after looking at the container cranes at the Port of Oakland, California while driving across the Bay Bridge.
Is it true? I have no idea. But the folks at thegirlandrhino.com, a small business based in Oakland, turned the legend into one very brilliant graphic t-shirt.
I bought one for me, and one for the kid.