When we figured out that Black Bart's Hidden Hoard would take us to a labyrinth in SOMA, I was certain what GC meant, but wasn't too pleased. Though it turns out I was certainly wrong. On 8th Street, there's a labyrinth mural with some texty-tiles on it. Wow, it looks puzzly and has nice text for data extraction. Why wasn't I "pleased" with the thought of using this great site? Well... I've scouted that site a couple of times. Each time, I couldn't handle the smell of pee. The labyrinth is in a little parking lot, and I guess drinkers tend to use the wall for quick relief. It smells pretty bad. Though maybe some GC might think that makes it a funny place to put a puzzle. (raises eyebrow snoutward)
I probably needn't have worried—Black Bart's Hoard was after some rain. When I visited the site again this week after some rain, it didn't smell.
But of course the Blackbartians had a different SOMA labyrinth in mind. This 8th St site is still ripe for puzzlehunt use. But maybe only for rainy-season puzzlehunts, or it might be pretty ripe in other ways, too.