Here's a single black-and-white snapshot I came across that has no dates or documentation whatsoever.
My best guess is that the photo was taken in Amsterdam sometime in the middle of the 20th century.
Here's a closeup of the four boys:
Why Amsterdam? For me, the obvious tip-offs are the canal in front of the boys and the clogs. Notice that at least one of the boys is wearing clogs. Also, notice the clogs sitting by the one doorway:
Anyone have any thoughts and/or insights to add?