Piazza Navona preserves the curved elliptical shape of Domitian's ancient Roman stadium. At its center stands Gian Lorenzo Bernini's Fountain of the Four Rivers (1651), supporting an ancient Egyptian obelisk crowned with the Dove of Innocent X. The four river gods (Danube, Nile, Ganges, Plate) represent the four cardinal quarters of the earth submitting to cosmic papal divine light.
The full decipherment and its observational protocol — where to stand, when, and what to watch for — are in the Rome field codex.
Or read the complete Florence codex free first.