Augusta Traiana was located in the Bulgarian part of the historical region of Thrace near the Bedechka river.
Todays name is Stara Zagora, an important economic centre of southern Bulgaria. It is located in Stara Zagora Province, about 231 km from Sofia. Its population is about 164,000.
Augusta Trajana / Stara Zagora is considered to be one of the oldest settlements in Bulgaria and Southeastern Europe. It was founded by the Thracians under the name Beroe (meaning "iron") about 6-5th millennium BC, with the Neolithic dwellings and the copper mine around the city being the oldest preserved ones in Europe. The area has been a mining region since Antiquity.
Under the Roman Empire, the town was renamed in honor of emperor Trajan to Augusta Trajana. Since the 6th century AD the city was called Vereja.
At the time of the Byzantine Empire, it took the name Irinipolis after a Byzantine empress. The fortifications around the town were reconstructed because of fear of Bulgarian attacks, but Irinopolis and the whole Zagore region were incorporated into Bulgaria under Tervel in 717 as a Byzantine gift in acknowledgement of the Bulgarian help to fight back the Arabs besieging Constantinople. The region was the first Bulgarian territorial gain south of Stara Planina. The town acquired the name Boruy.
In the year 1122 Stara Zagora (Beroia) was the site of a battle between Byzantine Emperor John II Komnenos and an invading Pecheneg army, the Battle of Beroia. The Pechenegs suffered a crushing defeat at the hands of John's Byzantine army, and many of the captives were settled as foederati within the Byzantine frontier.
Stara Zagora was conquered by the Ottomans in 1371. The town's name was again changed to Zheleznik (a Slavic translation of Beroe) in 1854 instead of the Turkish Eskizagra, but was renamed once again to Stara Zagora in 1870. After the liberation of Bulgaria from Ottoman rule, it became part of autonomous Eastern Rumelia before the two Bulgarian states finally merged in 1886 as a result of the act of Unification of Bulgaria.