I can’t tell you where I was when I took this picture because it will give it away; however, I will give you the hint that I was not in Colorado. This was taken while I was on a vacation where I was able to see a lot of things I had never seen before and visit some very memorable historic sites. I also had the opportunity to learn about things I hadn’t given much thought to in the past – like the subject of this photo.  Maybe you have seen one of these before, but didn’t know what you were looking at, so let’s see how close your guess can come.