Most people know that Toronto has a lost subway station--the infamous Lower Bay--but what's often left out of the story is how it got abandoned by the TTC. After all, why bother to build a station only to mothball it for several decades? The answer lies in a failed TTC experiment to create three subway lines out of two stretches of track: the Yonge-University line (as it was in the 1960s) and the new Bloor-Danforth line.

The scheme, known as interlining, meant riders could catch a train at, say, Greenwood and get downtown via Union without changing. The same system applied to eastbound trains. Riders could get on at Dundas West and get off at Eglinton without switching at St. George, Spadina or Yonge. Lower Bay enabled two separate routes to pass through the Yorkville station without having to share platform space. Despite presenting some advantages, the plan only lasted six months from the opening of the Bloor-Danforth line.

During the brief interlining experiment, the TTC--ever-imaginative with the names of its subway lines--offered riders the Bloor-University-Yonge, Danforth-University-Yonge and the familiar Bloor-Danforth lines on its promotional material. Today's familiar yellow and green designations for the YUS and Bloor-Danforth lines were yet to appear.

The rollsign on the front of the subway trains and the old "Next Train" displays are the TTC's most visible leftover relics of interlining. Instead of always reading "Kipling," "Kennedy," "Downsview" or "Finch," the signs would change to indicate the endpoint of the next train to save any hapless riders being whisked off against their will.

As you might imagine, the system wasn't without its issues. As Transit Toronto points out, a passenger heading east at Bay would have the choice of two different levels and run the risk of missing a train simply by virtue of being at the wrong platform when the train arrived. The same problem applied heading west at St. George.

Interestingly, a customer survey conducted at the time found those in favor and those against interlining were matched for numbers. Most simply didn't care one way or the other.

After just six months, the TTC decided to can interlining and stick with fully separate Yonge-University and Bloor-Danforth lines. The arrival of the Spadina line meant the second platform at St. George remained vital while Lower Bay was bricked up and abandoned when trains stopped passing through.

Today, Lower Bay has an almost legendary reputation amongst those with an interest in lost Toronto landmarks. Though rarely seen by regular subway riders, signs of its existence are still evident to those who pay attention: the mis-matched green tile used to cover over the stairs from the current platform at Bay, and the weird light visible down the tunnel from a westbound train at Yonge are often the first clues.

Having an unused subway station hasn't been all bad for the TTC. TV crews and filmmakers often rent the space as a filming location--chances are if you've seen the TTC on film, it's represented by Lower Bay. The TTC even owns an alternative set of signs for the platform to make it look like a stop on the New York subway.

In 2009, Absolut Vodka held a promotional party at Lower Bay. We've even listed the costs involved if you decide to rent the space for yourself--the kicker is you have to keep two trains at $700 an hour in the platform to deal with the risk of people falling on the tracks. Unless you've got friends in high places or plenty of cash to spare, the best way to see Lower Bay is to wait until the TTC next runs a tour or closes Upper Bay--something it does quite infrequently--and get ready with a camera. If you can't wait, check out the images and videos below.

MORE IMAGES AND VIDEO:

Looking along the Lower Bay platform.

A subway train at Bay showing "via Downtown" on its rollsign.

The TTC's stock of New York subway signs.

Passing through Lower Bay.

A tour of Lower Bay on open day.

Images: "Lower Bay" by Vlad TO, "Next train - Same as the Last Train" by The_cheeseman and "MTA/New York" by laurie.mcgregor in the BlogTO Flickr pool. All other images courtesy of Transit Toronto.