Remains of the Arch of Augustus in the Forum Romanum, July 2012

The Arch of Augustus was the triumphal arch of Augustus, located in the Roman Forum. It spanned the road between the Temple of Castor and Pollux and the Temple of Caesar, near the Temple of Vesta. Dedicated in 29 BC, it commemorates the Battle of Actium (31 BC) against Mark Antony and Cleopatra.

An inscription was found in the same location in 1546 AD, with a dedication to Augustus, so the identification of the arch is certain even though very little remains of the arch itself. Its appearance is known from Augustan coins. It had three passageways, the first such arch in Rome, and served as a model for the Arch of Septimius Severus, which was the model for the Arch of Constantine.

Text from: en.wikipedia.org/wiki/Arch_of_Augustus,_Rome