Walls never serve their original purpose for long, but are repurposed as tourist attractions. The Great Wall of China, Hadrian’s Wall (what is left of it), the Roman Empire’s limes(fortified border) have all become tourist attractions. This is also the case with those two virtuoso works of poured concrete, the Maginot Line and Hitler’s Atlantic Wall. The Berlin Wall has come and gone, as has the Iron Curtain. Now the “Iron Curtain” was a figurative wall in Mr. Churchill’s famous speech, but it had its concrete manifestations in guard houses, machine gun emplacements, and forests of fence and barbed wire across the map of Europe. President Trump is now calling for a Wall of Steel along the U.S.-Mexico border and I imagine that this wall, if actually built, will one day be a rust stain across North America and a monument to folly.