> You cant retrofit subways to existing cities How many million people lived in London, Paris, Moscow or Tokyo when they started building their respective subw

> You cant retrofit subways to existing cities How many million people lived in London, Paris, Moscow or Tokyo when they started building their respective subways? The answer is 2.5 million, 3.3 million, 3.8 million, and 8 million, respectively. And all of those were started before 1930, so it was actually possible with the technology 100 years ago.