Sargasso of Lost Starships by Poul Anderson

Drogobych lay before them.

The city stood on the open gray moor, and it had once been large. But its outer structures were long crumbled to ruin, heaps and shards of stone riven by ages of frost, fallen and coveted by the creeping dust. Here and there a squared monolith remained like the last snag in a rotted jaw, dark against the windy sky. It was quiet. Nothing stirred in all the sweeping immensity of hill and moor and ruin and loneliness.