The Ara Pacis: Resetting the Sundial of Augustus

Work by archaeologists at the University of Indiana has overturned a long-standing theory about two monuments raised by the first Roman Emperor, Augustus, and perhaps also cast a new light on his ideas about religion and government.

View of the Ara Pacis (Creative Commons, Manfred Heyde)

In 13 BC, after Augustus had returned from a three-year expedition to Gaul and Hispania, the Roman Senate voted to dedicate an altar in his honour. It was to be called the Ara Pacis or “Altar of Peace”, intended to celebrate the tranquility which Augustus had brought to the Roman Empire after a century of civil war. The Altar was dedicated in 9 BC, and although not large in scale is both beautiful and steeped in allusion to Augustus’ religious policy and his vision for the resurrection of the Empire. Resurrection, even in this context, is not too strong a word. The altar is covered in realistic depictions of indigenous burgeoning foliage, suggesting an almost elemental return of life to a land once sunk in winter and despair. On friezes around the altar are depicted processions of the Roman imperial family and other dignities engaged in sacrifice. Their expressions are grave and dignified, an example of the piety and sober behaviour which Augustus hoped to encourage amongst Romans after the selfish and irreligious violence of the civil war.

The "Tellus panel" from the Ara Pacis (Creative Commons)

The cultivation of an apparently neglected religion as a cure for the evils which had beset both Rome and the character of its people was one of Augustus’ primary policies. The idea is perfectly expressed in one of Horace’s Roman Odes (III.6.1-8):

Delicta maiorum inmeritus lues,
Romane, donec templa refeceris
     aedisque labentis deorum et
     foeda nigro simulacra fumo.

Dis te minorem quod geris, imperas:               
hinc omne principium, huc refer exitum.
     Di multa neglecti dederunt
     Hesperiae mala luctuosae.

(Although without guilt, you will pay for the sins of your ancestors, O Roman, until you restore the tottering shrines of the gods and the images stained with black smoke. Because you make yourselves lowly before the gods, you rule: to this point lay every undertaking, and to it every result. The neglected gods have given many woes to wretched Italy.)

Yet, if one were to accept Horace’s idea that the Romans should make themselves lower than the gods (dis te minorem… geris), there was something that jarred about the Ara Pacis. Sited near it on the Campus Martius was a 70-ft high red granite obelisk – the Obelisk of Montecitorio – which had been brought back from Egypt in 10 BC. The pavement around the Obelisk had been marked with lines so that it might serve as a sundial – all well and good – but according to observations which had been made by archaeologists over the last 50 years, the ensemble was designed so that on the day of Augustus’ birthday (23rd September) the shadow from the tip of the obelisk should fall across the centre of the Ara Pacis.

There were many ideas circulating during that time about Augustus’ almost cosmic role. The whole of the Aeneid, the Roman foundation epic written by Virgil just before this time, suggests that Augustus was fated by Jupiter to bring peace to Rome and extend its dominions across the earth. Yet there is something that always seemed to me excessive about the Sundial of Augustus; a suggestion that there was some grand coincidence of the cosmos looking down and bringing Augustus to birth. If the Altar was ultimately dedicated to the gods, then a proclamation of Augustus’ heavenly grandeur in a monument of piety to the traditional goods looks out of place; it is hardly dis te minorem… geris.

Yet, the new research about the sundial has brought this old theory crashing down. By computer simulations and the use of astronomical data, they have found that the Obelisk was actually designed not to point to the altar on Augustus’ birthday, but on 9th October – the Festival of Palatine Apollo. The revelation makes much more sense of the monument. Augustus was known for his dedication to Apollo: he attributed his victory at the 31 BC Battle of Actium (where he routed Antony and Cleopatra and assured his victory in the Civil War) to Apollo’s presence. A sundial which paid tribute to the guiding hand of Apollo over Augustus’ affairs and the peace of the Roman Empire is much more in keeping with Augustus’ own history and his vaunted piety to the gods, handing the ultimate tribute for Roman peace and victory not to himself, but them.