In this amazing aerial photo, you can see the old Logan Square elevated terminal on what once was known as the Metropolitan 'L'.
At the terminal were two platforms, a rail inspection shop and a rail yard. Built by the Metropolitan West Side Elevated Railroad and opened in 1895, this was the northwestern terminus until the route was extended, first, to Jefferson Park via the median of the Kennedy Expressway (I-90/94), with plans to later extend it to O'Hare.
In this photo, you can see construction on the subway extension to Jefferson Park has begun, which would be completed and opened in 1970, diverting all trains into the new, modern subway and onward through Avondale before merging into the expressway.
The subway station at Logan Square (with entrances just north of the square) and its station counterparts thru Jefferson Park were designed by the famous Chicago architecture firm Skidmore, Owings & Merrill who'd, in the same era, designed such famous buildings as the Sears Tower and John Hancock Center.