Metro, subway, underground, the tube

I can think of four iconic underground networks around the world. Plus one...

1. New York

Even tourists won't be acting that funny in the subway, if they just read first the clear instructions: How to ride the subway.

2. London 

London Underground, the tube, that just celebrated its 150th anniversary!

3. Paris

Where you can get auditioned by the transportation officials and then get up on the stage i.e. the metro stations!

4. Tokyo

Tokyo Metro (I especially like the mobile phone restriction!)

And then we have...

Helsinki

Which is quite cute actually. Best way of getting back and forth the line is to buy a day ticket. You can get one for 1 to 7 days. One day day ticket is 8 euros. 

Have a nice journey!