Walking down Mulberry Street, gelato alla nocciola in hand, I couldn’t help but watch the old man wearing a vest and a coppola animatedly talking to his friend in Sicilian. If I had snapped a picture, you would have guessed that they were in Italy, but the background gave it away.

They were in Little Italy in New York City. Behind them was a colorful, abstract mural of Audrey Hepburn, created by street art muralist Tristan Eaton. A curious juxtaposition, but both belonged: those men who...