Largest man made structure?

[l008com]

I didn't know what forum to put this in, but anyway. The great wall of china is often thought of as the largest thing on earth.

http://answers.yahoo.com/question/index ... 450AAblRRI

I wonder if anyone has ever thought about the USA & Canada's trail network for the prize? Its one continuous gigantic metal structure. Its certainly not the tallest, but it's pretty big in all other dimensions. I imagine it's volume is pretty extreme too, don't forget to count the ties.

[scharnhorst]

I know that the Russian Railroad net work is one of the largest Railroad operations in the world by way of Route Miles, Locomotives, Railroad cars, emploees, and passenger traffic.

http://en.wikipedia.org/wiki/Russian_Railways

[l008com]

Oh, well in that case forget i brought it up