Michelangelo redesigned the Campidoglio in 1536, creating an oval plaza centered around the bronze equestrian statue of Emperor Marcus Aurelius. The pavement is inlaid with a 12-pointed star pattern (Caput Mundi, 'Head of the World'), symbolizing the cosmic hub from which Roman roads radiated to the ends of the earth.
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.