One crazy thing about Japan, specifically Tokyo, is you never know what is below your feet. Take this passageway for example that runs underneath a busy street above it. I would venture a majority of roads around stations actually sit on to of passage ways and parking lots like this one. You never really know until you go downstairs.
I once had to park in an underground below a major artery that also had the elevated expressway on top of it. That was pretty interesting. When there is little space you build up and down I guess.
Undergrounds in Japan are awesome. In Tokyo, subway stations can be very huge, it's really a small town underground. You can easily be lost, searching for an exit. You walk, you walk, and when you go upstairs sometime you are directly in a building. It's very convenient when it's raining, you may go where you want without going outside !
Well said. Yes, several stations are like small cities and are easy to get lost in. There are parking structures underground all over the city too..