Unternberg is a village in the Lungau area of Salzburg, in the very south-east of the province. Unternberg has a total population of approximately 1,000 and is well-known within Salzburg for one main attraction: Schloss Moosham, the castle of Unternberg. It is the third-biggest castle in Salzburg after the Fortress Hohensalzburg and Fortress Hohenwerfen.
Schloss Moosham was first mentioned in 1193 and until today, it is private property. However, visitors are welcome nonetheless: The castle is open for visitors, many of which are on vacation in the Lungau and come to Unternberg for a day-trip.
The museum that you can find within Schloss Moosham is also private. Its permanent exhibition focuses on local findings of Roman artefacts as well as torture tools and toys from early modern days - supposedly used in witch trials, but more likely to be commonly applied with ordinary criminals.
Attractions of Unternberg & Surroundings
The parish church of Unternberg is somewhat unusual and worth a closer look: The "Pfarrkirche zum Heiligen Ulrich" was a Baroque building until 1978, when the architect Heinz Tesar added a new and modern extension.
The surroundings of Unternberg offer good opportunities for hiking and other Alpine summer sports. However, these opportunities are probably not fundamentally better than what you would find in other parts of the Lungau, a generally scenic stretch of land.
If you want to go skiing from Unternberg, you will probably be better off if you have your own mean of transport (aka a car). Unternberg is one of the communities in the Lungau where Samson processions are still done.
Municipalities of the Lungau
Official Website of Unternberg
German Wikipedia on Unternberg
Tourism Website of the Lungau Area
Official Website of the Salzburg province