Building a Stone Bridge

It challenges me when I want to draw a something that looks fairly simple, and my hand just doesn't get it. Here's an example of what I'm talking about: I had the idea to paint a stone bridge. I looked for a photo as a reference. I'd never drawn one before and I wanted a photo that wasn't too complex.

 

I found a picture that I liked.Well! I had such a hard time capturing the arc shape of that bridge.
 I drew on layers of tracing paper so I could make my corrections without ruining the expensive paper. 

I kept trying and erasing. I'm only showing you some of my attempts.  I was at this for hours, but  I finally got a drawing I could work with. Here are a couple of the preliminary drawings and the unfinished painting.  I did enjoy the challenge, and I will probably do it over, differently. It was much more difficult than I imagined.  I learned a lot from this experience.