Flavia Solva was a municipium in the ancient Roman province of Noricum. It was situated on the western banks of the Mur river, close to the modern cities of Wagna and Leibnitz in the southern parts of the Austrian province of Styria. It is the only Roman city in modern Styria.
The Celto-Roman dwelling on the banks of the Mur river that should later become Flavia Solva was founded around year 15. while Noricum was still a Roman protectorate. This precursor consisted of a small cluster of wooden buildings, and did not follow a grand layout plan. It is believed that the Celtic element in its population came from the hill settlement on the nearby Frauenberg which had a tradition tracing back to neolithic ages. Very few remains from this phase have been found.
Shortly after the annexation of Noricum as a Roman province, the place was made a municipium around year 70 by emperor Vespasian who added the name of his Flavian dynasty to the local name Solva which might have referred to the Frauenberg settlement (which remained important as a worship site for Isis Noreia, a local adaptation of the Isis cult), or to the nearby river Sulm. The construction activity that followed resulted in an almost entirely new city of stone buildings, with a layout that approximated the ideal of a Roman provincial municipium: rectangular insulae (sized about 60 by 70 meters) within a grid of broad (ca. 6 m) gravel-paved streets. Some of the apartment houses in these blocks had hypocaust heating, similar to what is known from comparable Roman cities; however, Flavia Solva had neither an aqueduct nor canalization. The 80 x 35 m ellipsoid amphitheatre (apparently the only one in Noricum) consisted of wooden benches on stone foundations.