If i read the first post correctly, then it is in the cone of an extinct volcano - so actually in a upthrusting finger of rock, the cooled magma in the vent with everything else eroded.

About the spiral street: I agree, it doesn't look very "spirally". Maybe try some kind of a laying S, if you know what i mean. If you just look at a spiral from one side, then the slope should appear higher at the edges, where the street seems to run towards the viewer. I hope you understand what i'm trying to say, otherwise just look at a spring from one side.