ATOP a towering, rocky ridge in Qazvin Province, Iran, in the quiet hills far from the bustle of the world, once stood a fortress untouched by rulers. In winter, it was covered in slippery snow, with the squalls of the north crushing the bones. In the scorching summer, the south winds whipped golden sand against its walls.

To reach this fortress, one must climb a steep, narrow, and winding path. Today, all that remains are a few fragmentary wall