Broken Circle

I went for a cycle through the Drum again as it is proving to be a good route to help me get back into cycling. On the way back as I was passing the old stables I noticed this window. There were four round windows, but this one was different then the others. The brick work around the window must have been damaged and fixed at some point, but left the stone circle slightly offset. I have been to the Drum many times but had not noticed this before. It's amazing to discover something 'new' in a very familiar place.