Starting from the 7th-6th century BC, Etruscan aristocrats competed in building grandiose tombs surmounted by mounds, to show everyone the importance and wealth of their families. The rituals of the cult of the dead were celebrated there, which should be understood as the cult of the ancestors who had brought prestige to the lineage. Inside they were decorated and painted, and precious objects and furnishings that were needed for life in the afterlife were placed there.
When Rome got in touch with the Persian and Hellenistic world, discovered the incredible splendor of the palaces of those sovereigns. Greece had been conquered with weapons and colonized, but in turn conquered Rome and colonized it with its culture and art.
Luxury thus became one of the symbols of power also in Rome, in the domus or in the city palaces of the most ancient aristocrats; arousing the criticism of Cato and others against excessive luxury and the abandonment of the severe customs of the Republican age.
Like their palaces, the tombs of the sovereigns served to show their wealth and therefore their power, starting with the Egyptian Pharaohs: their earthly homes have disappeared, while those of the afterlife – the Pyramids – are still standing.
In the Hellenistic context, the most famous example is the Mausoleum of Halicarnassus (present-day Bodrum in Turkey), which was one of the Seven Wonders of the world. It took its name from Mausolus, the king of Caria, and was built in 350 BC. by his wife Artemisia, who called upon the most famous artists and sculptors of the time to decorate it (Briasside, Leochares, Timoteo and Skopas). It had a large rectangular base on which the actual tomb stood with tall columns, and on top there was a Quadriga of the Sun, probably driven by them.
Since the Republican era, also in the Roman and Italic world, the tombs of the most famous people were built along the consular roads to have maximum visibility. Aristocratic families competed in building increasingly imposing tombs, which were the symbol of the power and prestige of their Gens. For example, we recall the Mausoleum of Caecilia Metella in Rome on the Appian Way and the Mausoleum of the Plautii in Tivoli, on the Via Tiburtina near the Ponte Lucano; both had a circular tower-like building covered in travertine, placed on a square base.
The most direct precedent of the Mausoleum of Hadrian was of course the Mausoleum of Augustus, the first imperial dynastic mausoleum in Rome. It had a square base on which stood a circular building covered in travertine. It was built in the Campus Martius, a site of great symbolic value where, according to legend, the apotheosis and ascension to heaven of Romulus, the founder of Rome, took place. Since the time of Julius Caesar (and even before), the funerals of the most important figures of the Roman world had been celebrated there.
Since there was not enough free space in the Campus Martius, Hadrian chose a nearby area, on the right bank of the Tiber: the Ager Vaticanus with the Horti Domitiae, which since long time had belonged to the Imperial House. A very important road passed nearby: the via Triumphalis, where the triumphal processions of the great Roman leaders took place. Hadrian proposed himself as the ideal successor to Augustus because, like him, he had brought peace to the empire after centuries of wars, inaugurating a new Golden Age of prosperity.
The Mausoleum of Hadrian was slightly smaller than that of Augustus, but it was the first grandiose monument encountered when arriving in Rome from the north. Like all Roman monumental tombs, it served to show the power of the emperor and his family. Like the Mausoleum of Halicarnassus, it had a Quadriga of the Sun on the top, driven by Hadrian himself, depicted as Sol Invictus.
The book «Castel Sant’Angelo. Mausoleum of Hadrian. Architecture & Light» (English edition) explains in detail the meaning of the Quadriga and the Mausoleum as a symbol of dynastic continuity and divine ancestry that legitimized his power. The book offers a new and unpublished reconstruction of its ancient appearance and of its transformations during the Middle Ages and the Renaissance up to the present day.