Without specifically looking for street art, I came across these several pieces over the course of a few months traveling in parts of Europe.
They may not be the very best examples of European graffiti, but they provide snapshots of the way street art is experienced in daily life—the surprise of finding a life-like depiction of a man lying on the street, visible yet hard to see; the humor of an old man looking coyly around a corner; the bold energy of a baby wailing; the appreciation of how a painting is framed by, and interacts with, its surroundings.