This point lies on the right bank of the Danube, about thirty kilometres east of Vienna, in Petronell-Carnuntum, and the lake is a good half hour's ride further south. What you have instead is something that most riders miss: the ruins of Carnuntum, once the capital of the Roman province of Upper Pannonia and a military base of the Danube frontier. In its time it held a legionary fortress, an amphitheatre and a city of tens of thousands, and several emperors passed through. Marcus Aurelius is said to have written part of his Meditations while on campaign here.
Most of what was built has been quarried away over the centuries, but a few pieces stand. The Heidentor, the pagan gate, is a freestanding arch of massive stone rising out of the fields, and it has become the symbol of the place. There is a reconstructed Roman quarter, with villas rebuilt using ancient techniques, and an archaeological park where excavations still go on every season. The flat farmland between Petronell and Bad Deutsch-Altenburg is rich in finds, and farmers plough up pottery fragments.
North of the villages lies the Donau-Auen National Park, one of the last intact stretches of floodplain forest in Central Europe. Poplars, willows and oaks stand in the wet ground, with white-tailed eagles overhead and beavers working the backwaters. A stop on the dyke path, with the broad grey river sliding past, shows why the Romans put their frontier here. The Danube cycle route runs right along it, so expect families on bikes.
For the rider, this is a quiet, flat, easy ending to a day on the road. The back roads through Rohrau, birthplace of Joseph Haydn, and the smaller villages are straight and lightly trafficked, with wide fields, wind turbines on the horizon, and a steady breeze that can push you sideways on exposed stretches. The Bundesstrasse into Vienna is faster but busier.
Petronell is small and has limited services, so go for fuel and a proper meal in Hainburg an der Donau, a town of about six and a half thousand with a medieval gate and wall, a few kilometres east. After a long day, a glass of Zweigelt and a plate of Wiener schnitzel at a village inn do the job, and you will still be in Vienna before dark.