The Miyanoharu Line that connected Oita and Kumamoto prefectures in Kyushu was a scenic wonder when it opened along its entire route in 1954, winding for 27 km through mountains and valleys and across no fewer than seven bridges in the town of Oguni in Kumamoto alone.

But back when construction of the railroad started in 1935, Japan was gearing up to wage war in China and those beautiful, arched bridges are believed to have been made of concrete reinforced with bamboo instead of steel bars, according to Keisuke Imao, a freelance writer who specializes in railways and maps.

"If that really is the case," Imao explained, "it would have been because the country lacked iron at the time as the United States had placed an embargo on exports to Japan."