Credit: U.S. Army via Twisted Sifter
During World War II, the most important technological infrastructure was composed of the factories that produced the weapons and vehicles used by the belligerent powers. To prevent those factories from being destroyed by enemy action, ingenious camouflage was deployed to make them invisible from the air; the United States enlisted Hollywood set designers to create entire fake towns that covered the factories.
Today, tech infrastructure is hidden for a different reason: Though our modern society depends on power lines, railroads, and wireless data broadcasts, our sense of aesthetics tends to recoil when the stuff is built near our homes. That's why we've developed a number of ingenious ways to hide this vital (but ugly) tech from sight.