This picture was taken at the Late Antiquity reenactment festival, in Carnuntum, in 2019. Late Antiquity is part of a larger era called Migration period, which also covers Early Middle Ages. As a reenactor myself, this period is to me twice as interesting Europeanly speaking : Late Antiquity represents the last time Europe was united as one state ; and Early Middle-Ages witnessed the birth of European cultural diversity, with meltings of various Roman and Germanic contributions.The photo shows the Emperor Valentinian reviewing his troops after the Adventus, a ceremony during which the emperor is welcomed by the citizens in the city.