History of the Ghost Station
Below the main platform for Bay station is an abandoned platform, which was used for only six months in 1966 when the Toronto Transit Commission (TTC) experimentally ran trains whose routes included portions of both the Yonge-University and Bloor-Danforth lines.
This abandoned platform is sometimes referred to as The Ghost Station or Lower Bay by the general public or Bay Lower by the TTC.
(click here for more info) 1966 subway map: