Reminds me of the northwestern area in Skyrim. Their is a dock out looking a rock structure similar to this. Can't remember where though considering I wasn't a huge fan of the game. Look awesome though!
Thank you very much! And no there is no particular set of brushes, in fact, the three main brushes I used in this piece are default brushes, (round hard edge, round soft edge, and the chalk brush), I used some other brushes but not that much