Niederösterreich (Lower Austria) is the north-eastern part of Austria. It is called Nieder-, which means low, because this area is mostly not part of the Alps. It borders to the Czech Republic, Hungary and even Slovakia, includes the capital Wien (Vienna), and south of Wien the Wienerwald, which is actually the end of the Alps on the east side. Most of the listed sights are actually in this piece of low mountains, which is part of the northern limestone Alps, which means it consists mostly of limestone and is karstified.
Allander Tropfsteinhöhle
Dreidärrischenhöhle
Einhornhöhle
Einödhöhle
Eisensteinhöhle
Graselhöhle
Schaubergwerk am Grillenberg
Hermannshöhle
Hochkarschacht
Johannesbachklamm
Erdstallmuseum am Kapellenberg Althöflein
Kohlerhöhle
Nixhöhle
Ötscher Tropfsteinhöhle
Ötschergräben
Paulinenhöhle
Erdöl-Erdgas Museum Prottes
Retzer Erlebniskeller
Schauplatz Eiserner Vorhang
Seegrotte Mödling
Steinwandklamm
Wienerwaldmuseum
Ysperklamm