The clock struck four, and I was lost in the city of Zaragoza. I meant to take the five-minute walk from my Spanish exchange summer school to my host family’s apartment on Calle Don Jaime. Distracted by street musicians and fascinated by chance encounters with structures that were already ancient when the first Europeans came to the shores of America, I had taken a few wrong turns and wandered into an unfamiliar barrio. I soon found myself in a...