Vienna began as a Roman legionary camp, Vindobona, on a terrace above the Danube, and its streets still follow some of the old lines. The camp itself was in what is now the inner city, around Hoher Markt, and the canabae, the civilian settlement that grew up beside it, spread out to the west and south with workshops, taverns, houses and cemeteries. The Gräberfeld, the field of graves, lay beyond, as Roman custom demanded. The remains here are mostly underground and under pavements, which suits a city that has built on every layer of its past.
Vindobona was a frontier post on the Danube limes, the long line of forts and watchtowers that marked the edge of the empire, and the legions stationed here guarded a river crossing and a trade route. Tradition says the emperor Marcus Aurelius died in the area in AD 180 while campaigning against the tribes north of the Danube, though historians argue about whether it was here or elsewhere. The Danube limes is now a World Heritage Site, and the sections in Vienna are part of that story.
Riding in Vienna is a different sport from the Alps. The city is compact and orderly, with trams, cobbles on some old streets, wet rails in rain, and sharp traffic lights that change quickly. The Ringstrasse, the grand boulevard around the old centre, is a pleasure to ride at a leisurely pace on a quiet morning, with views of the opera, parliament and town hall, but avoid the rush hour, when it is slow and tense. Parking for motorcycles is easier than for cars, and many streets have designated bays, so look for those rather than leaving the bike on the pavement.
Fuel is easy to find on the main roads in and out of the city, though the immediate centre has few stations, so top up at the outskirts. Food ranges from the classic coffee house, with its newspapers and slices of cake, to the wine taverns called Heurigen on the edge of town, where new wine and cold cuts are served in gardens in summer. A morning is enough to see the Roman remains at Hoher Markt and walk through the old quarter, and then you can ride up to the Kahlenberg for the view.