Lascaux Detroit
The Cave Paintings of Detroit

The terminus of the Dequindre cut is in the Rivertown area along the Detroit River and just east of the Renaissance Center.  This line once carried commuters from the northern suburbs to the downtown skyscrapers.

Abandoned in the 1980's, it is now being eyed by casino developers as a dedicated automobile conduit automobile from I-75 to the casinos. 
{Update note: Since this was written, the casino locations were decided to be at other sites.]