[exit82]

Seems to me this picture was taken on a Sunday morning, so there is little street or pedestrian traffic, as stores would be closed.

Traffic in the street would have shown up as a blur, as the exposure said to be seven minutes.

[TChad]

Seems to me this picture was taken on a Sunday morning

Traffic in the street would have shown up as a blur

Your explanation makes sense. Street traffic would show up as blurry areas in the middles of the lanes. The cobblestones are not blurry.

The photographer might have chosen a Sunday for exactly that reason. He wanted a sharp photo despite the long exposure time.