Garabit viaduct

Wrought-iron arch railway viaduct, completed 1884. Built by Gustave Eiffel's company, with Maurice Koechlin as structural engineer, in France's Cantal region. Before the tower in Paris, there was this. A single parabolic arch with a 541-foot span lifts one railroad track about 400 feet above the Truyère river, and the latticework is so open that the whole structure looks drawn in pencil against the valley. Eiffel's achievement was economy: a huge arch raised in record time with very little material, and you can see that thrift in how much sky shows through it. The site is remote, so pair it with a drive through the surrounding uplands.