Mauterndorf sits in the Lungau, the high, bowl-shaped basin in the far south-east corner of Salzburg province, where the Taurach river collects itself before heading north. You arrive here with the Niedere Tauern behind you and the Katschberg ahead, and the basin floor is already over a thousand metres up, which is why winters here are properly cold and why the light on a clear September morning feels so thin and bright.
The village is dominated by its castle, a medieval pile that has been owned by Salzburg's archbishops, a string of noble families and, in the early twentieth century, a wealthy doctor who restored it and brought up his godson there. That godson was Hermann Göring, which is the sort of footnote the village tends to mention quietly, if at all. The castle today is open to visitors, and the old market square below it, with its painted facades and fountain, is a pleasant place to park the bike and walk in boots that are slightly too warm.
Mauterndorf is a crossroads rather than a destination in itself. The old trade road over the Radstädter Tauern runs north from here, and the road east climbs to the Katschberg pass, about 1,640 metres, on its way into Carinthia. Both are well graded and easy to enjoy: wide enough for a bit of rhythm, steep enough to keep you honest on the hairpins, and usually busy with campervans in July. If you want the road to yourself, aim for the early part of the day or the weeks either side of the main holiday rush.
For practical matters, the village is small, about twelve hundred people, so treat fuel as something to confirm rather than assume. Sankt Michael im Lungau, five kilometres away, is the larger neighbour and sits on the Tauern motorway, which makes it the safer bet for a full tank before the passes. For food, this is potato country: the Lungauer Eachtling, a local potato variety, turns up on menus in dumplings and dishes that taste far better after a cold ride than they sound.
Stay a little longer than you planned if the weather is clear. The ring of high peaks around the basin catches the evening light well, and the air smells of cut grass and woodsmoke, which is about as good as a rest stop gets.