We drove along the Rhine River past Koblenz just to see the shining white Marksburg Castle scintillating in the sun high up on top of the hill. I wanted to feature it in a key scene in one of my historical thrillers, and I had to see it first. It convinced me that the location was almost impossible to access up an almost vertical hill. My characters would be challenged by it. Despite its white color, it was dark and mysterious with the weight of history. With a torture chamber intact I am reminded that it dates back 800 years. The lords who lived her exacted frightful tolls on those who sought to pass down the river beneath it. If they didn't pay they were killed. Who knew what struggles and intrigues occurred inside those impenetrable stone walls? It was a challenge to the imagination to picture them. Certainly you could spend all day doing so as the castle stood all so far away, unreachable, unfathomable, aloof, and beyond your ken.