Riddle: A long and hard object on a wet surface

You have to be smart to know the answer to that riddle. Unless you looked at the picture already...then that's cheating!

I love this bridge! It is a gentle but sharp sweep of blade-like footbridge on top of this River in Maribor. Designed by Arhitektura doo all of you (Footbridge in Maribor by Arhitektura d.o.o posted in ArchDaily. ) you wonder how this bridge will support itself. Do we have the technology already to make this bridge erect this way? Do we viagra on concrete mixtures already?