Piazza Barberini and the Capuchin Crypt

The Site: Today a busy traffic circle, the piazza centers on Bernini's masterpiece fountain of a Triton (merman) spouting water into the air from a shell held to his lips.

The Secret: Dan Brown missed a golden opportunity to work into the plot the Capuchin Crypt, a grisly set of chapels decorated with the bones of dead monks—wall of skulls here, scapula chandelier there—a few doors up Via Veneto, beneath Santa Maria Immacolata Concezione church.