It sits on a major European waterway, the Danube, which after Vienna exists into the plain lands - Hungary, Romania. Started as a Roman settlement, Vindobona,

It sits on a major European waterway, the Danube, which after Vienna exists into the plain lands - Hungary, Romania. Started as a Roman settlement, Vindobona, it has been strategically important for a very long time. Paris without the Seine would equally be irrelevant. London too.