Mystery Cable?

"Keeping one of the buildings from falling over?" Nice!

I work in the Temple Opera Building and in the hallways there are several old pictures of the building.  I checked them out and while I didn't see the cable in question, there were other cables going from building to building across Superior Street.  They seem to be the cables used to suspect the power lines for the old street car system.  So, maybe this cable is leftover from those days.

I'm going to hazard a guess that these are for hanging decorations. Here's the evidence:

In 1963 you can see the wires on the Temple Opera Block and Old City Hall
Temple Opera 1963
Old City Hall 1963

You can also see one on the Hunter Block at 1st Ave W
Hunter Block 1963

Here's some evidence of the decorations in 1972
Christmas City of the North 1972

This 1940s picture doesn't seem to have it
Temple Opera 1940s

Still, at this point it might be to hold the building up.

I'd say decorations is a good guess. There's 3 wires in that area, 2 going across the street, and one diagonally across the intersection. There's another diagonal one 1st ave west too, as well as evidence of another diagonal cable on the corner of the old KBJR building. 

There's was probably tons of these downtown, but were removed when building were remodeled, torn down, or replaced.