In the morning, the 70-foot long corridor pinned between Ambiance and Blast 805 is a quiet place.
Stuck on the walls, gifting a particular smell, sits gum of all ages, known as its hangout spot -- Bubblegum Alley.
"If locals think of SLO, a lot of people are disgusted by this," said James Papp, local historian. "But outside, I would say Madonna Inn and Bubblegum Alley are the most iconic. And you really can't have it described to you. I tell people about it and they go 'Eh' and they come here and go 'Oh.'"
Papp is also a member of the SLO Cultural Heritage Committee. His knowledge of downtown's history is vast and that includes knowing where and when the alley came to life.
"There is nothing like this. This was of its time, a first off. You look at this, and its impressive. It's a community effort. It's a weird community effort but it's better than having the gum on the ground. And there is kind of a weird magnificence about it."
Move over, Seattle. Our gum wall came first. So the biggest question is, when did it start? Papp says the history shows us the first piece of gum slapped that wall in the late 1960s.
"People around at the time said it started with the high school students as a kind of prank, then it was picked up by Cal Poly students. Then it was a tourist thing," Papp said. "It's really a thing for outsiders, it became quickly a thing for outsiders."
It really didn't start to get attention until the 1970s.
Weird Al Yankovic name dropped the wall in his 1978 song "Take Me Down," a song dedicated to San Luis Obispo.
If you're new in town
Then you'll wanna look around
But you don't know where to begin
Well, there's Bubble Gum Alley
And the local car rally
Not to mention the toilets at Madonna Inn
National publications began picking up stories on these walls draped in gum.
"The old parts fade, but people put on new parts and you have these colorful dots all over," Papp said. "It's very psychedelic. It's a 60s monument that is still going on."
Those visitors leave a mark, whether its just a piece of gum, or a message of love. People come here to say, "I walked through Bubblegum Alley and survived."
"It combines gum chewing which is an ancient habit with the tendency of people wanting to leave their mark in some way. This is kind of a not very intellectual way of leaving your mark, but why do you have to leave your mark intellectually?"
It is not a landmark yet, but that doesn't mean the city won't work to preserve the art so many people have helped create.
"I do forsee it happening," Papp said. "I think the cultural heritage committee for the city of San Luis Obispo which is our preservation commission, we discuss this periodically. It always has the 'ick' factor but people recognize its importance."
Bubblegum Alley is under consideration for preservation in the Downtown Concept Plan.