Carnuntum was a Roman city, a legionary base and, for a time, a capital. The Fourteenth Legion, the Gemina, was stationed here from the first century, and the camp, with its great barracks and parade ground, guarded a crossing of the Danube where the Amber Road from the Baltic met the river. By the second century it was the capital of the province of Upper Pannonia, with an amphitheatre, baths and a population of tens of thousands. The emperor Marcus Aurelius is said to have spent part of the German wars here, and tradition holds that he wrote some of his Meditations in the camp.
In AD 193 the legions on the Danube proclaimed their governor, Septimius Severus, emperor at Carnuntum, and in 308 Diocletian and other emperors met here to try to patch together the tetrarchy. After that the city faded, and in later centuries it was a quarry for the villages around it. The Pagan Gate, a ruined triumphal arch standing in the fields, is the landmark, and an archaeological park has reconstructed houses, a gladiator school and the amphitheatre. The legionary camp, on our list, has largely vanished under fields, but the outlines are being revealed by surveys and excavations.
The country around is flat and fertile, with vineyards on the low hills and the broad Danube floodplain, now a national park, the Donau-Auen, with its wetlands, oxbows and sea eagles. Roads along the river are easy and fast, with scenery that is pleasant rather than dramatic, and the busy road to Bratislava, only forty kilometres away, is an alternative route. The Neusiedler See, a huge shallow lake, is a short ride to the south. Summers can be hot, and spring and autumn are best.
Hainburg an der Donau, with its medieval gates and walls, is seven kilometres away and has fuel and cafes. Bad Deutsch-Altenburg is a small spa town with a church on a hill. The Carnuntum wine region produces red wines, such as Zweigelt, that go well with the local food. Tickets to the archaeological park are modest and the park is generally open from spring to autumn, so check before you go.