Cliffs, quarries and memories of a deposed queen

Climb the hill along the city wall north of Dongdaemun Gate and look east. On the far side of the valley, you'll notice houses clustered around a crescent-shaped cliff. If you venture into the valley beyond it, you'll find more of these oddly curved, stark granite cliffs jutting out of the hillsides. These are not geological formations, but remnants of…