One San Francisco Octothorpean Puzzle Ahead of Opening Day

I'm not a super-duper expert about location-based puzzles. I don't know exactly when the world is going to change and thusly mess up a puzzle. But I know that it happens. This weekend, I found a nice location-based puzzle that fits the hashmarkish theme of The Octothorpean Order… but I wonder if the site will last. I'm not even that sure it will last a few months until the game properly opens. So I'm improperly jumping the gun with this one. Here's a link to Music Mural, a puzzle in San Francisco's Mission District.

If I were you, I wouldn't shlep all the way out to The Mission just to solve this. It would be a lot of shlepping for not-so-much solving. But the next time you're heading out there anyhow, swing on by…uhm, wherever this puzzle is. If it's still there.