✅ The Mausoleum of Hadrian, today's Castel Sant'Angelo, is the monumental dynastic tomb that the emperor Hadrian had built on the banks of the Tiber river, starting from 130 AD; it was completed in 139 AD, one year after his death.

✅ Imitating the Mausoleum of Augustus, the Mausoleum was cylindrical, covered with blocks of travertine. It had an earth mound crowned by a probable temple, on top of which it seems there was a colossal bronze Quadriga of the Sun, led by the emperor Hadrian portrayed as Sol Invictus. A first clue of a possible archaeo-astronomical significance.

✅ At the end of the fifteenth century the Mausoleum it was transformed into a fortress, covering it with a brick curtain, adding battlements, altering the original structures with new rooms; however, it seems that about 70-80% of the Roman structures have been preserved within this modern 'shell'.

✅ From the Elio Bridge a majestic rectangular vestibule was accessed, revetted with precious marbles. It gives access to a curved corridor, which goes up making a full 360° turn, and ends into a second vestibule, located exactly above the first, but ten meters higher.

✅ The second Vestibule gave access to the Hall of Urns, which was the sepulchral chamber: it had three niches oriented towards east, north and south. It was lit by windows-tunnels, which were built in such a way as to capture the sun's rays only on the days of the summer Solstice. Even today the light enters from those two windows, illuminating the three underlying niches, where the imperial sarcophagi were placed.

✅ Those illuminations had a precise symbolic meaning, linked to the imperial cult, the dynastic succession and the divinization after death of Hadrian and of the other emperors.

‼️ Special Illuminations in the Tomb of Hadrian.