[WATCH] New York City Built the World’s Most Expensive Subway

New York City is home to some of the world’s most iconic buildings. But its most impressive structure might actually be underground. With the swipe of a Metrocard, you can ride from the Bronx to midtown to Brooklyn to Queens all on the same network. But it’s not always seamless. Now, New York is undergoing its biggest subway expansion in 50 years with the Second Avenue Subway.