K.Shkorpil was the first who mentioned about Augustae in the archaeological literature. He located it in "Kaleto" near the village of Hurlets at the mouth of the river Ogosta and gave a brief description and a plan of the fortress.
Augusta was mentioned in some Roman and early-Byzantine sources, as follows: "The Map of Refftinger", "A Guide of Emperor Antonin", "A List of the Official Ranges in the Roman Empire", "About the Buildings" - Prokopi Kessariyski, "Geography" - an unknown author from Ravena and "World History" - by Teophilact Simokata.
The fortification system of the Camp of Augustae and the late-antique and early-Byzantine city of Augustae were researched from 1973 till 1987. The first fortification of the camp was made of wood and soil. It was not studied but marked only. Most probably it was built in the 50s of the first century, when the camp was situated in this location. Later the camp was surrounded with a stone fortress. The preserved part of the western fortress wall with its three rectangular towers and the western gate were researched. On the western-northern fortress wall, two rectangular towers outflanking the Northern gate of the camp fortification were found.
The preserved part of the fortification of the city of Augustae was researched. It included the western, northern and a part of the eastern fortress walls with two gates, two corner towers and sixteen intermediate. The gates were on the northern and western walls. They were flanked with two U-shaped towers. Corner towers were almost circular. Three of the intermediate towers of the second period were rectangular, and the rest 13 were U-shaped.
The sources and the data from the archaeological excavations showed that the fortress wall, surrounding the city of Augustae, was built in the first 10 years of the IIIrd.c., Immediately before the first Gothic invasions. It existed till 582, when it was destroyed by the Avars and was not restored any more.
К. Лука. Керамика от средновековния пласт над развалините на късноан-тичния град Augustae до с. Хърлец, община Козлодуй, Северозападна България. – В: Сборник в чест на акад. Д. П. Димитров, София, 2013, 618-640.
С. Машов, Г. Ганецовски, К. Лука. Спасителни археологически проучвания на римски кастел и ранновизантийски град Августа при с. Хърлец, община Козлодуй.– Археологически открития и разкопки през 2003 г., София, 2004, 104-105.