on the underground

[ripley]

Hi folk! I hope you are all fine...
I would like to know what this sentence mean..
I went to the theatre on the Underground.
What does on the Underground mean?
Does it mean that the theatre is placed along the underground line and so under the earth, or just above the underground?
Ripley

[RonBee]

My guess is that the person went to the theater by means of what we Americans would call the subway. The destination would not itself have to be underground for a person to get there by means of the Underground.