"The Underground" should also be accepted since that is the common term used by a large percentage of Brits.
i agree with you. i've just lost a heart because of this. it's a shame they don't understand british english. percebe1950
Another Briton bites the dust :(
Duolingo isn't case-sensitive, but I still feel I should point out that the Underground usually refers to the Tube (or tube). For the generic thing one shouldn't capitalise the word.