Augusta Traiana, Roman city archaeological site in Stara Zagora, Bulgaria

Augusta Traiana was a Roman city on the site of today's Stara Zagora, Bulgaria, enclosed by walls of about 50 hectares with roughly 40 towers, 11 of which have been studied. Its grid of straight streets, forum, odeon, theatre, baths, temples and markets dates mainly to the reign of Marcus Aurelius (161–180). A central paved street ran east–west, and near the walls a mosaic of Dionysus's procession was found in 2011.

Trajan granted the Thracian settlement of Beroe self-government in 106 CE and renamed it Augusta Traiana, which became Thrace's second city after Philippopolis. It prospered under Marcus Aurelius, minted its own coins from 161 to the late 3rd century, and was visited by Septimius Severus, Caracalla and Diocletian. It was again called Beroe in the mid-4th century, when it was a leading Christian centre, and was largely destroyed by Gothic, Hunnic, Avar and Slavic invasions.

The name Augusta Traiana honors Emperor Trajan and reflects Roman rule over the region. The remains of marketplaces and bathhouses show how residents organized their daily lives and gathered in these public spaces.

Visitors today can explore the archaeological excavations and see the outlines of city walls, the marketplace, and the bathhouses. A nearby Roman museum displays coins, sculptures, and mosaics that illustrate daily life in the ancient city.

The 2011 Dionysus mosaic found near a city wall shows two dancing bacchantes and a satyr holding a staff and a leopard skin; one woman plays castanets, the other maracas. It is made of stones about 1 cm across, with finer tesserae for details, and was restored with funding from the American Research Center in Sofia and America for Bulgaria.