Bubblegum Alley

Bubblegum Alley is a tourist attraction in downtown San Luis Obispo, California, known for its accumulation of used bubble gum on the walls of an alley. It is a 15-foot high and 70-foot long alley lined with chewed gum left by passers-by. It covers a stretch of 20 meters in the 700 block of Higuera Street in downtown San Luis Obispo.
Data from: en.wikipedia.org