The Perfect 43.3-Meter Sphere. Rebuilt by Emperor Hadrian between 118 and 125 AD, the interior forms a mathematically perfect sphere inside a cylinder. The interior diameter (43.3 meters) equals the height from the floor to the Oculus apex.
The Open 9-Meter Oculus. Acting as the unblinking eye of Sol Invictus, the Oculus admits a beam of sunlight that moves across the interior coffered dome like a solar clock.
The Equinox Doorway Alignment. On the Vernal Equinox at solar noon, the sunlight beam passing through the Oculus hits the exact junction between the ceiling dome and the entrance doorway archway, illuminating the emperor as he entered the temple.
Each carries its full hermetic decipherment and an observational protocol — where to stand, when, and what to watch for — in the Rome field codex.
Or read the complete Florence codex free first.