This thread is a wonderful archive in its own right and all credit to those who selflessly populate it. A thought about the locations. In trying to determine these, without the benefit of captions, peripheral or seemingly unimportant details might help. I have picked up on some posted by others, like shop front signs, house and building architecture, landscape, leaves on trees or not for dates. Uniforms not helpful if the resolution is not good for badges. So, if the column are all wearing uniforms, are they thrown open, even if wearing a greatcoat, indicating the weather was very warm at the time. What weapons are the guards carrying, what vehicles are they in, or are in picture? Just a few examples to think about. While a contemporary caption is the winner, it may be that looking at the whole collection of clues in a picture helps.