On the edge of Town

So this is where it starts then, I have often wondered.
Went on a long bike ride this morning, to try and help clear the excesses of the last three days in Holland.
Just as I crossed the Medlock Bridge on Cambridge Street near the "Hotspur Press" I saw this up on the wall.
There must be a story attached to this.....
I wonder if there are any more signs around Manchester still in existence.