The Ara Pacis Augustae is an altar in Rome dedicated to the Pax Romana. The monument was commissioned by the Roman Senate on July 4, 13 BC to honour the return of Augustus to Rome after three years in Hispania and Gaul and consecrated on January 30, 9 BC. Originally located on the northern outskirts of Rome, a Roman mile from the boundary of the pomerium on the west side of the Via Flaminia, the Ara Pacis stood in the northeastern corner of the Campus Martius, the former flood plain of the Tiber River and gradually became buried under 4 metres (13 ft) of silt deposits. It was reassembled in its current location, now the Museum of the Ara Pacis, in 1938, turned 90° counterclockwise from its original orientation so that the original western side now faces south.

The Pax Romana is a roughly 200-year-long period of Roman history which is identified as a golden age of increased and sustained Roman imperialism, relative peace and order, prosperous stability, hegemonic power, and regional expansion. This is despite several revolts and wars, and continuing competition with Parthia. It is traditionally dated as commencing with the accession of Augustus, founder of the Roman principate, in 27 BC and concluding in AD 180 with the death of Marcus Aurelius, the last of the "Five Good Emperors".