A 12th-century castle ruin perched on a wooded ridge above the eastern edge of Vaduz, the Wildschloss ("castle in the wild") is one of Liechtenstein's better short hikes. The path climbs from the upper edge of town through forest for around 90 minutes one way, with a steady ascent and good views back over the Rhine valley as you climb.
The ruins themselves — fragments of walls, a partial tower, a cistern — are picturesque rather than substantial. The point is the walk and the view. From the top, you look down on Vaduz Castle from above, with the Swiss mountains on the far side of the Rhine and the upper Rhine valley stretching south toward the Alps. Sturdy shoes; the path is slippery after rain.