The keep of Saalburg Castle was originally the symbol of the fortification on the castle hill, visible from afar. The tower with a diameter of approx. 10 m was originally 35 to 40 m high. In 1913, it collapsed for unknown reasons. Most of the rubble was disposed of in the Saale valley. Part of it was leveled on the site to create the flat surface visible today. Directly in front of the tower was a 3 m wide shield wall with a moat in front of it. It sealed off the castle from the plain to the east. Behind the shield wall was a 2 m wide curtain wall that surrounded the entire castle area. The castle's multi-storey residential building was located on the western side of the rocky spur on the edge of the slope that fell steeply down to the Saale. In the 14th century, most of the fortifications and buildings were demolished and smaller half-timbered buildings were erected in the castle courtyard. In the first half of the 16th century, the bailiffs of Gera built a castle complex on this site, which presumably fell victim to a town fire. A stone with the alliance coat of arms of Gera and Beichlingen has been preserved.