I swear to god I never knew this place existed until Richard and I stumbled across it on our way to the aquarium.
"The Market Theater Gum Wall is a local landmark in downtown Seattle, in Post Alley under Pike Place Market.
Similar to Bubblegum Alley in San Luis Obispo, California, the Market Theater Gum Wall is a brick alleyway wall now covered in used chewing gum. Parts of the wall are covered several inches thick, 15 feet high for 50 feet.
The wall is by the box office for the Market Theater, and the tradition began around 1993 when patrons of Unexpected Productions' Seattle Theatresports stuck gum to the wall and placed coins in the gum blobs. Theater workers scraped the gum away twice, but eventually gave up after market officials deemed the gum wall a tourist attraction around 1999. Some people create small works of art out of gum."