How does a city make music? Listen to the beep beep of horns (Piiph Piiph in Afaan Oromo), the rumbling of trains like drums along the tracks, the sounds of dogs and cats, the bleating of livestock, the crashing of goods in the market. Taken together it is a symphony that only a civilization could produce, the music of life and livelihoods and trade and travel. If you stop to appreciate each sound in turn, you can hear the music of a city like...