The Seggau Roman Stone Wall

The Roman stone wall at Seggau Castle, erected in 1831, is a monument of supra-regional importance. The Roman-period stone monuments are not only important testimonies of the provincial Roman culture, but also provide insights into the eventful history of their reuse. These stones, dating from the Roman Imperial period, were originally funerary structures, honorary monuments and dedication altars, or parts of them. They were mostly made of local Eastern Alpine marble, and came from the funerary roads or public squares of the Roman city of Flavia Solva.

In late antiquity, a time of various threats and unrest, these structures and monuments were demolished and a massive tower was built from their stone blocks on the Leibnitz castle hill. In the Middle Ages, next to this tower, on a slightly lower level, the castle of the Archbishop of Salzburg was built; the northern part of this castle hill, together with the tower, was given to the newly founded diocese of Seckau in 1219. The diocese in turn integrated the tower into their castle complex or built around it. In the early 19th century, the Old Tower had to be demolished due to acute danger of collapse. Due to its size and massiveness, the demolition took place in two work phases over several years. In the masonry as well as in the foundation, numerous stone monuments from the Roman period with their artistic reliefs and inscriptions were brought to light again. After the final demolition of the tower in 1831, the cultural-historical significance of thesstones was recognized and they were bricked into the ground floor of a new corridor in front of the medieval wing of the building. This museum-like arrangement, taking into account the impression of these stones, gave rise to the Roman stone wall that is still preserved today.

In the original design concept of 1831, the Roman stone wall was strictly rectangular in the form of a sharp-edged fenestration in the plaster. Thus, basically only the relief or inscription fields of the stone monuments were made visible, mostly without the profiled frame. All broken surfaces and parts lying outside were hidden under the plastering at that time. In order to avoid the impression of the fragmentary character of the stones, missing parts of the framing and the inner fields were supplemented with mortar. This Roman stone wall, which follows a design-ornamental principle and is reminiscent of a baroque picture gallery, was particularly exposed to the weather due to its delicacy and the poorly adhering plaster on the stone surface.

During subsequent renovations of the facade, parts of the original framing were made visible in correspondingly larger plaster windows. In 1986, the original concept was abandoned and the wall was plastered in gently rounded transitions to the broken edges of the stones. However, a cement-bound restoration plaster was used at that time to prevent moisture damage. This dense plaster, to which a cement slurry was additionally applied, acted like a waterproof plaster, causing damage to the masonry’s structure on the inside. This also affected the Roman stones.

In the course of the façade renovation of the Roman stone wall from May to September 2019, the exterior as well as the embrasures of the three passages were freed from this damaging cement plaster of 1986 and approximated to the appearance of 1831 by a new plastering according to monument preservation guidelines while improving weather protection. This extensive restoration measure made it possible to document the wall as well as the individual stones in their unplastered state for the first time since 1831. With the help of laser scanning and Structure-from-Motion (SfM), comprehensive data material was generated, with the help of which a detailed documentation of the unplastered and current condition of the Roman stone wall in Seggau Castle was achieved. The results of this work include 98 3-D models of the Roman stones on the outside of the wall as well as those in the three passages, plus a 3-D model of the Latin building inscription from 1831. In 2020, the restoration of the wall surfaces in the passage behind the Roman stone wall will be continued. In this corridor, another 36 Roman-period relief and inscription stones as well as a coat-of-arms stone from 1651 and a year plate from 1491 are walled in. Also, based on the current state of research, a contemporary presentation of the Roman stone wall for interested visitors is to be designed.

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Text: Paul Bayer BA, Mag. Dr. Stephan Karl