So I was browsing Google Earth the other day and I found this strange formation near Râmnicu Vâlcea, at about 45°07'N 24°16'E
It's an almost circular region, about 40 km in diameter which to my eyes looks like a multi ringed impact crater, but then again it's near a mountain chain so it could be just some random feature created by the converging tectonic plates. But what could cause the hills to be arranged in this strange manner?