Semmering is where Lower Austria hands over to Styria, and it does so at a saddle of roughly 985 metres in the last eastern bulge of the Alps. The Rax and Schneeberg massifs stand to the northwest, the Hirschenkogel rises right above the village, and the whole place has the faintly faded air of somewhere that was once the most fashionable thing in the empire.
That fashion came with the railway. Carl von Ghega drove the Semmering line through here in the early 1850s, the first true mountain railway in Europe, with viaducts stacked in two tiers and fourteen tunnels clinging to the slopes. It now carries UNESCO status. Vienna's wealthy followed the track and built villas, grand hotels and sanatoria among the beech and spruce, and you can still read that era in the woodwork and the tall verandas along the lanes. Long before the railway, the old road over the pass was the way south to Graz and the Adriatic, and in the early twentieth century the climb served as a famous hill-climb course for racing cars.
On a bike the old pass road is the point of the exercise. From Schottwien on the Lower Austrian side it climbs in a run of tight hairpins through woodland, with the viaducts of the railway visible across the valley as you go. The surface is generally decent, the bends are properly tight rather than merely suggestive, and the gradient never stops being interesting. Beyond the top it drops more gently toward Spital am Semmering and Mürzzuschlag. The modern expressway burrows under all of this, which is exactly why the old road is quiet on a weekday and why the lorries are somewhere else.
Practical matters are simple. Semmering village itself is small, with a few cafés and hotels but no reliable fuel, so tank up before the climb or in Mürzzuschlag, the nearest real town about twelve kilometres away on the Styrian side. Early autumn is lovely, with mist in the valleys and cool, clear air at the top, but even in May a shaded hairpin can be damp, and in winter snow turns the pass into a problem for two wheels. Stop at the top for a coffee and look at those old hotels. Some are lovingly restored, some are still waiting for somebody with a great deal of money.