Off Higuera Street between Broad and Garden you’ll find Bubblegum Alley. 
I saw this on TV, we had to stop. Also, it was on people’s Foursquare lists of “to-do” when you are in San Luis Obispo. What the heck, right? Read a little about it below:
It’s kinda gross, kinda cool. A rainbow of ABC gum lining each side of the alley.
There’s a sweet scent of bubble gum in the air with an immediate waft of stink, rotten, moldy…ew.
The kids were trying to figure out how long some of those pieces had been there. Also they wondered if they kept building upon it, if the alley would become more and more narrow. I started getting claustrophobic.
Some of the gum fresh, some stringing down, some marked into letters and messages, and some pinned up with coins.
I thought for a moment we’d all chew some to add to the wall, we didn’t. I got a crazy sense of germophobia and forbid the kids to put their hands near it. Plus, there were bees everywhere. Probably one of the strangest places I’ve ever been.
I’ve read about this before. Looks cool but is gross 😛 I think my family would get keeped out walking through there…
ewwwww,who knows what kind of dieases some of those ppls chewed gum would have,,an to touch it omg! no way ,no how,,you are braver than I am ,I wouldnt go near it,id be afraid id catch something,that is just totally gross