The Solarium Augusti (also called Horologium Augusti) was an

ancient Roman In modern historiography, ancient Rome refers to Roman civilisation from the founding of the city of Rome in the 8th century BC to the collapse of the Western Roman Empire in the 5th century AD. It encompasses the Roman Kingdom (753–509 BC ...

monument in the Campus Martius constructed during the reign of

Augustus Caesar Augustus (born Gaius Octavius; 23 September 63 BC – 19 August AD 14), also known as Octavian, was the first Roman emperor; he reigned from 27 BC until his death in AD 14. He is known for being the founder of the Roman Pri ...

. It functioned as a giant solar marker, according to various interpretations serving either as a simple meridian line or as a

sundial A sundial is a horological device that tells the time of day (referred to as civil time in modern usage) when direct sunlight shines by the apparent position of the Sun in the sky. In the narrowest sense of the word, it consists of a flat ...

. The obelisk belonged to Egyptian Pharaoh

Psamtik II Psamtik II ( Ancient Egyptian: , pronounced ), known by the Graeco-Romans as Psammetichus or Psammeticus, was a king of the Saite-based Twenty-sixth Dynasty of Egypt (595 BC – 589 BC). His prenomen, Nefer-Ib-Re, means "Beautiful s theHeart ...

History

It was erected by the emperor Augustus, with the 30-meter Egyptian red granite Obelisk of Montecitorio, that he had brought from Heliopolis in ancient Egypt. The obelisk was employed as a

gnomon A gnomon (; ) is the part of a sundial that casts a shadow. The term is used for a variety of purposes in mathematics and other fields. History A painted stick dating from 2300 BC that was excavated at the astronomical site of Taosi is the ol ...

that cast its shadow on a marble pavement inlaid with a gilded bronze network of lines, by which it was possible to read the time of day according to the season of the year. The ''solarium'' was dedicated to the Sun in 10 BCE, 35 years after Julius Caesar's calendar reform. It was the first solar dedication in Rome.

Campus Martius

The Solarium Augusti was integrated with the Ara Pacis in the Campus Martius, aligning with

Via Flaminia The Via Flaminia or Flaminian Way was an ancient Roman road leading from Rome over the Apennine Mountains to ''Ariminum'' (Rimini) on the coast of the Adriatic Sea, and due to the ruggedness of the mountains was the major option the Romans had ...

, in such a way that the shadow of the gnomon fell across the center of the marble altar on 23 September, the birthday of Augustus himself. The obelisk itself was set up to memorialize Augustus' subordination of Egypt to the control of the Roman empire. The two monuments must have been planned together, in relation to the pre-existing Mausoleum of Augustus, to demonstrate that Augustus was "born to bring peace", that peace was his destiny. According to the ''Cambridge Ancient History'', "the collective message dramatically linked peace with military authority and imperial expansion."

Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic '' ...

remarked that in the course of time it had become incorrect, and offered several explanations for the shift. The obelisk was illustrated, supported by a reclining figure, on the base of the Column of Antoninus Pius. The obelisk gnomon was still standing in the 8th century CE, but was thrown down and broken, then covered in sediment; it was rediscovered in 1512, but not excavated. In a triumphant rededication, the ' Montecitorio obelisk' was re-erected in

Piazza di Montecitorio The Palazzo Montecitorio () is a palace in Rome and the seat of the Chamber of Deputies, the lower house of the Italian Parliament. History The palace's name derives from the slight hill on which it is built, which was claimed to be the ''Mon ...

by Pius VI in 1789.

Archaeology

Edmund Buchner Edmund Buchner (22 October 1923, Ittling near Straubing – 27 August 2011) was a Germans, German ancient historian and former President of the German Archaeological Institute (Deutschen Archäologischen Instituts, or DAI). He graduated in 1953 f ...

excavated some sections of the calibrated marble pavement of the Solarium Augusti under the block of houses between

Piazza del Parlamento The Palazzo Montecitorio () is a palace in Rome and the seat of the Chamber of Deputies, the lower house of the Italian Parliament. History The palace's name derives from the slight hill on which it is built, which was claimed to be the ''Mons ...

and

Piazza San Lorenzo in Lucina The Minor Basilica of St. Lawrence in Lucina ( it, Basilica Minore di San Lorenzo in Lucina or simply it, San Lorenzo in Lucina; la, S. Laurentii in Lucina) is a Roman Catholic parish, titular church, and minor basilica in central Rome, Italy. ...

. Recent studies have challenged Buchner's reconstruction of the Solarium as a full sundial, maintaining that the archaeological and textual evidence indicates a simple meridian line, marking the changing noontime position of the Sun in the course of the year.Peter Heslin, "Augustus, Domitian and the So-Called Horologium Augusti", ''The Journal of Roman Studies'', 97 (2007: 1-20).

Notes

References

*The broad context of the Augustan iconographic program, of which the Solarium Augusti is part, is presented in ''The Power of Images in the Age of Augustus'' by Paul Zanker; University of Michigan Press; 1988.

External links