The 21st of April is considered a special day each year for the Pantheon, because at midday the light that streams through the oculus shines on the metal grill above the large entrance door, which causes light to reflect throughout the entire courtyard, illuminating the whole interior of the Pantheon. What makes this date all the more significant is the fact that the 21st of April is considered the anniversary of the day that Rome was founded. It is also rumored that on the day when Rome was founded, the ruling emperor had a god-like illumination surrounding him, which was the result of the rare reflection of light throughout the Pantheon.