Although the Roman temple of Évora is often called Temple of Diana, any association with the Roman goddess of hunt stems not from archaeology but from a legend created in the 17th century by a Portuguese priest. In reality, the temple was probably built in honour of Emperor Augustus, who was venerated as a god during and after his rule. The temple was built in the 1st century AD in the main public square of Évora - then called Liberatias Iulia – and modified in the 2nd and 3rd centuries. Évora was invaded by Germanic peoples in the 5th century, and at this time the temple was destroyed. Nowadays its ruins are the only built vestiges of the Roman forum, in an open square fronted by the cathedral and the bishop's palace.
The ruins of the temple were incorporated into a tower of Evora Castle during the Middle Ages. The base, columns and architraves of the temple were kept embedded in the walls of the medieval building; the temple-turned-tower was used as a butcher shop from the 14th century until 1836. This new use of the temple structure helped preserve its remains from further destruction. Finally, after 1871, the medieval additions were removed. Restoration work was directed by Italian architect Giuseppe Cinatti.
The Évora temple still has its complete base (the podium), made of both regular and irregular granite stone blocks. The portico of the temple, now missing, was originally hexastyle, six columns across. A total of fourteen granite columns are still standing on the north side of the base; many of the columns still have their Corinthian-style capitals sustaining the architrave. The capitals and the bases of the columns are made of marble from nearby Estremoz, while the columns and architrave are made of granite. Recent excavations indicate that the temple was surrounded by a water basin.