Subway posters are huge, limited edition posters printed by the record company to promote a new album or single at the time of release. They are typically seen on billboards, subways, and music store windows, etc. 
All the posters in this gallery measure 60 x 40 inches, except the white "We2R1 LP" poster which measure 40 x 28 inches.
The "Who's That Girl?" picture below shows the scale of the poster against a 12" vinyl.

Love Is A Stranger - This poster is not an official Subway Poster. It is a home made poster that I created. It measures 60 x 40 inches, and included in this page just for fun.

In 2005, Eurythmics released "Ultimate Collection". The promotion of this CD included 7 posters. One featuring the CD cover, and six others, each featuring an iconic Eurythmics song, with a lyric from each song.
Below are all 7 posters issued in subway size: