Mystery, landmark, 3D model: The Heathen's Gate of Carnuntum through the ages
By Nisa Iduna Kirchengast - Editors: Daniel Kunc, Thomas Mauerhofer
The so-called Heathen's Gate in Carnuntum is one of the most important monuments along the Austrian Danube Limes and serves both as a landmark of the ancient city and as a symbol of Austria's Roman heritage to this day. Its history and significance spans centuries, but its appearance has changed over time.
Located around one kilometer south of the civil town of Carnuntum, the Heathen's Gate was probably built during the reign of Emperor Constantius II in the middle of the 4th century. Numerous found coins and reused votive altars suggest this. Known in the Middle Ages as the “Heydnisch Tor” (pagan gate), due to the idea at the time that everything Roman was pagan (= not Christian), it was even regarded as the tomb of a giant. In fact, however, it was originally a four-gated building (Latin quadrifrons, “four gates”). In other words, unlike its current appearance, the original “Heathen's Gate” had four pillars (and therefore also four portals). Its sides were around 15 meters long and it could have been up to 5 meters high. The exact function of the gate as a triumphal monument or a marker of Carnuntum's location has not yet been fully clarified.
Despite its uniqueness as a Roman ruin, the Heidentor (Heathen's Gate) was neglected by researchers for many decades and was only examined in detail between 1998 and 2001. A round pedestal in the middle of the building could possibly have served as the base for a statue, but no corresponding remains have been found. Its interpretation as the starting point for the provincial survey with the groma, a Roman measuring instrument, is also uncertain. The exact relationship of the Heidentor to the road connections and surveying axes in the area around Carnuntum remains a mystery, as the connections to the south and north run around 50 to 100 m further east. The exact orientation of the Heidentor to the cardinal points also raises questions.
The archaeological investigations at the Heidentor at the end of the 1990s marked a milestone in its research history. Due to stone robbery into the 20th century and numerous restoration measures, most recently in 2023, the external appearance of the monument has changed considerably. Although what can be seen today can hardly be described as an ancient original structure, interesting details were uncovered during the restoration analyses, such as traces of ochre, blue and purple, which indicate that it was once painted.
To document the transformation of the listed monument, which has also been a UNESCO World Heritage Site since 2021, the Heidentor recently became part of Europeana's “Twin it!” EU campaign. The project of the European Ministries of Culture and national cultural institutions aims to implement high-quality 3D digitization of symbolic material cultural assets and thus establish high quality standards in the three-dimensional documentation of buildings and monuments.
As part of this Europe-wide project, the Heidentor is being reconstructed in three historical periods: around 1840, around 1907 and in its current state. These models make it possible to document the changes to the monument over time and make them accessible to a wide audience. High-precision drone and photogrammetric images as well as the use of GPS technology enable precise measurement and reconstruction and record them for future generations.