What Roman forum in Rome was built by Augustus and features the Temple of Mars Ultor?

The Roman forum built by Augustus and featuring the Temple of Mars Ultor is the Forum of Augustus.

Augustus vowed the temple before the Battle of Philippi in 42 BC, presenting it as a shrine to Mars the Avenger after the defeat of Julius Caesar’s assassins. The forum and its temple were finally inaugurated in 2 BC, after decades of planning and construction.

The complex combined political symbolism with practical functions. Its porticoes and exedrae displayed statues of distinguished Romans, while the Temple of Mars Ultor hosted ceremonies, foreign-policy discussions, and meetings concerning war and triumphs. Augustus also placed the recovered standards taken from Crassus at Carrhae there after their return through diplomacy with Parthia in 20 BC.

A common mix-up is confusing it with the Forum of Julius Caesar, which is adjacent and older, or the much larger Forum of Trajan, completed more than a century later. The Forum of Augustus is identified specifically by its association with Mars Ultor.