The rest of the world is building subways like crazy. The U.S. has pretty much given up

The most spectacular way to cross the Bosphorus is by boat, but the most impressive way is by subway. Istanbul’s Marmaray Line, completed in 2013, links Asia and Europe by way of an eight-and-a-half-mile undersea tunnel. The ride is so fast and so smooth, it feels like a hovercraft. When my dad and I traveled to Istanbul last year, we were prepared to witness the city’s beauty and stand in awe of its history. But what really blew us away was the city’s transit system.  “It’s...