Untere Burg, Medieval castle ruins near Schellenberg, Liechtenstein.

Untere Burg, also called Burg Alt-Schellenberg, is a castle ruin on a hill at 590 m on the Eschnerberg, about 150 m above the Rhine valley north of Platta. Its visible walls cover roughly 50 by 20 m: the trapezoidal tower building, the ring wall with the older gate, and the outer bailey. A reconstructed bread oven stands in the courtyard near the old gate.

The Schellenberg nobility began construction around 1250, with tower structures and defensive walls added later. The site developed over centuries into a notable fortified structure of the region.

The ruins show medieval defensive architecture visible in the preserved stone walls today. Visitors can understand how a medieval fortress was designed and used.

Access is via a hiking trail along Eschnerberg with no entrance fees. It is wise to wear comfortable hiking shoes and allow time to explore the surrounding area.

The name Untere Burg refers to a castle system consisting of two separate fortifications, with this structure being the younger one. Despite the naming, it developed into a self-contained fortification with its own strategic importance.