There's a bridge near Stazione Trastevere that separates Porta Portese and Piazza della Radio. If you happen to be walking under it when a train passes above, you suddenly know what it's like to be inside a drum when someone's playing a solo.
There's a man who lives in the underpass who runs a makeshift bookstore. Dozens of books, some which look almost new, are neatly displayed on old card tables with prices drawn in magic marker on folded index cards. It's hard for me to fathom the hardship of living without shelter, but I find that man's very existence beautiful.
Once in a while he has a radio playing when I walk by. A few evenings ago I was walking to Piazza della Radio for some late-night food. When I passed the bookstore, I caught the chorus of Leonard Cohen's 'Who By Fire' echoing through the static. Hearing that song at all is a rarity. Encountering it at that very moment was enough to make me realize that half the songs Cohen ever wrote were sung for people like the bookseller.