There is a (very small) chance that a reader (or two) may ALREADY KNOW what is going on here,
will be able to immediately solve the riddle. In this case you may choose to solve
I doubt that readers will be able to find this specific image on the web elsewhere (yet one never knows on the deep web). So another approach must be used to meet the challenge.
This image is a scanned postcard. From where? Depicting what?
I believe there are enough elements, in the image, to solve this (small) riddle. Provided you know how to search, of course :-)