The Gum Wall, located beneath Pike Place Market in Seattle, is a quirky brick wall covered in used chewing gum. It started in the 1990s when theatergoers stuck their gum on the walls, creating a colorful and sticky spectacle. Despite occasional cleanings, the wall has become a popular tourist attraction and local landmark, with visitors adding new gum to the wall regularly. Some see it as gross, others as art, but one thing's for sure - it's definitely unique!