In 1870, a New York millionaire secretly built a 300-foot underground railway. Decades before the city's modern subway network took shape, people forgot it existed

Long before New York Citys modern subway system opened in 1904, a millionaire had already built a secret underground railway beneath Broadway. The unusual pneumatic transit experiment drew hundreds of thousands of riders but ultimately disappeared after political opposition and an economic crisis brought the ambitious project to an end.

Raccontata daeconomictimes.indiatimes.com