China’s first ever subway runs through the heart of Beijing. Proposed in 1953 as a way to ferry soldiers from their barracks on the outskirts to the city center, the 13-mile, 16-station metro line opened in 1969 after years of debate, including one over the decision to ultimately knock down the 700-year-old Dadu City Wall that once protected the emperor of the Yuan Dynasty.

Beijing’s Line 1 didn’t opened to the public until the 1980s. And in the years that followed its initial run, subway expansi…