Another note I just thought of - look at the cobblestones above - full size it - and you will see the actual BUMP created by the Bump Map almost starts looking like "spikes" - not smoothly rounded bumps.

When I first applied it, the Bump Depth was set to 1.000 and the shadows really overtook the color of the Color Map - which already had shadows of its own built-in.

THIS is why I keep photo-based texture bumps down to a minimum unless I'm going for something over the top - like peeling and cracked paint on crusty old walls - in which case I would make it even higher - like 5-8!