Concept - Caverns

I've never done a concept sketch this quickly. It took me a little over an hour to finish this. And I actually like it. What's going on? Yay.

I came out with a massively bruised knee, but no injury has ever been worth it as much as that one was. What was there, below the streets and sidewalks that you walk and bike and drive over, were colossal caves, caverns, tunnels. You could get lost there. I did. And without the light, what would you do? There, in that deepest, darkest black where the sun wouldn't hit even if it were out, how would you find your way back? I came back with stories, with the remainder of gorgeous rock formations burned behind my lids, and an even more pressingly, consumingly urgent need to go back again. Tomorrow.