5x5
"Evidence of the prehistoric earthwork was first observed by Anthony Murphy, who runs the website Mythical Ireland. Since the heatwave and drought have been revealing crop marks of ancient castles and Iron Age forts in Wales and England in recent weeks, Murphy decided to fly his drone over the Boyne Valley to see if anything new was showing up in his area."
https://www.smithsonianmag.com/smart-news/drought-reveals-giant-4500-year-old-irish-henge-180969650/