Piazza NavonaHistory & audio guide · Rome

That elongated shape is no accident: you're walking on a 1st-century athletics track. Here stood the Stadium of Domitian, raised around the year 86 for the agones —Greek-style athletic contests— with marble stands for more than 30,000 people. When the Empire fell, the stadium was devoured by houses and taverns. But its outline remained, and over it the Baroque traced a theatrical square. They even flooded it in summer, so the nobility could drift in gondolas as if in Venice.

The name tells the whole story: from in agone —"in the contest"— the people slurred the word into Nagone, Navone, Navona. And at the center, Bernini sculpted the Fountain of the Four Rivers, with a startled river standing for the Río de la Plata; facing it, the church by Borromini, his great rival, in a duel of marble that's still there.

But it isn't all the glory of popes. On a side wall there's a carved face that seems to scream: the trace of an innkeeper who, the story goes, mocked Pope Sixtus V without knowing whose wine he was pouring. Days later he was executed. Warning or tribute? Like everything in Rome —if it isn't true, it's at least believable. Ruthy tells it to you in five chapters, standing right there.