Barcelona, Spain (2017) - During my travels, I’ve noticed that European cities often have bollards lining their sidewalks. These short posts (often made of metal) are used to divert traffic from an area, and often keep pedestrians safe. Dating back to the 17th Century, bollards were originally used to moor ships, and often made from burying old cannons. As they began to be specifically made, many of them retained their cannon-shape, including a little round knob at the top.
While walking through Barcelona, I noticed that some local graffiti people decided to add some color to those knobs, so we’d see rainbows of bollards lining the streets.