Down Street was an underground station in London that opened 1907 and closed 1932. The station was part of the Great Northern, Piccadilly & Brompton Railway. The station closed due to low usage of passengers and some trains didn't even stop at the station when it was active.
The station was used as a bunker for Winston Churchhill and his War Cabinet during WWII.
What's left today:
The station building still stands today and has been converted into a reatail outlet. Most of the station underground is still there today, but the platforms were bricked up during WWII and can only be seen from a passing train.