Seattle's Pike Place Market attracts throngs of tourists every day but follows a cobbled street down beneath the market and you'll discover something altogether less wholesome... Seattle's infamous 'Gum Wall'.
More than just a wall, it's a 50-yard stretch of alleyway whose walls are covered in gum left behind by visitors. The tradition started in the early 1990s and, after a couple of futile attempts to get rid of the gum, market administrators declared the Gum Wall a tourist attraction in 1999.
Visitors don't just leave their gum, they use the wall to make art and leave messages for people. It's even used as a spot to declare love.
Thirty years on from its inception, the Gum Wall continues to delight and disgust in equal measure.
In fact, today's Gum Wall is the product of just a few years of gum-sticking. The alley was steam-cleaned four years ago, with workers removing more than a ton (907 kilos) of gum. As soon as it was cleaned, the gum started appearing on the walls again.
And in the age of Instagram and social media, the gum wall keeps attracting more and more visitors, all looking for that perfect selfie moment.
With another five-yearly cleaning expected soon, gum chewers will soon have a new, fresh brick canvas to decorate when they visit Seattle.