The "Korkenzieher" (German for "Corkscrew") is a lookout tower on a mountain called "Fuchsberg" that is located between Traismauer and Sitzenberg-Reidling in Lower Austria's Traisental.
The lookout tower looks like a corkscrew and from the top you have a wonderful view on the surrounding areas.
Here's the description of the hiking trail to this lookout tower.