CIMRM Supplement - Mithraeum. Kempraten, Switzerland.

A Mithraeum was discovered in 2015 during rescue archaeology at Zürcherstrasse 131, Kempraten, overlooking lake Zurich. The location was in the vicus of the Roman settlement. Coins from the 3rd century AD were found, and also some as late as Valentinian and Theodosius, suggesting that it ceased to function at the end of the 4th century. An complete steatite altar was found, dedicated to "Invicto Mitre", and right next to a large cult image. Other dedications to "Invicto" or "Deo invicto" were also found. A weathered large sandstone altar dedicated to Invictus with the top 3-4 lines preserved was found.

Bones of poultry and pig were discovered. Also more than 50 rock crystal fragments and hundreds of crystal chips were recovered from the central aisle. Only 1 other Mithraeum had such a feature: that at Martigny where crystals were attached to the ceiling to symbolise the stars, reflected from the lamps below. The ritual cave at Zillis also had crystals.¹

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From an article by Hans Jakob Becker, 28th August 2015.²

Neben den drei in den letzten Wochen auf einem privaten Areal bei Kempraten, direkt am See gefundenen Kalköfen, fanden die erstaunten Archäologinnen und Archäologen Mauerreste, die sich nach ersten Grabungen als Teile eines Kultraumes entpuppten. Hier wurde nach ersten, noch ungesicherten Erkenntnissen dem Gott Mithras im Rahmen einer Mysterienreligion gehuldigt. Der Raum, 7,5 Meter Mal 20 Meter gross, war nur für Männer bestimmt. Funde von Bergkristallen deuten auf den Gott Mithras hin. Als Bestätigung für die religiöse Bestimmung des Raumes gilt ein Sandsteinfragment, das ein Antlitz zeigt. Daneben wurden viele Knochen von Jungtieren gefunden, was auf kultische Opferungen hinweist. Ein rekonstruiertes Bild zeigte eine vage Vorstellung dieses Kultraumes, der sich vom Fels zum Wasser hinzog. Eine Konstellation, die für die Kultausübung wichtig war. Noch ist Vieles nicht erforscht. Man weiss nur, dass in Martigny und Orbe ähnliche Bauten gefunden wurden. In addition to three lime kilns, found right next to the lake in recent weeks on private land at Kempraten, the astonished archaeologists found the remains of walls, which on excavation turned out to be part of a temple. The first indications are that the god Mithras was worshiped here as part of a mystery religion. The room, 7.5 meters by 20 meters in size, was intended only for men. Finds of rock crystals indicate the god Mithras. A sandstone fragment showing a face is treated as confirmation of the religious use of the site. In addition, many bones of young animals were found, suggesting ritual sacrifices. A picture of a reconstruction gives a general idea of this cult space, which ran from the waterside to the rock. There is a constellation, which was important for the cult myth. Most of the site is still unexcavated. It is only known that similar buildings were found in Martigny and Orbe.3

The site was presented to visitors by the Canton archaeologists Martin Schindler and Regula Ackermann. The excavation director is Hannes Fluck, and trainee archaeologist Sarah Lo Russo showed them around. The kilns were 6m high, and the stone came across the lake.

An exhibition of finds is scheduled for November.

Update: a new article in 1815.ch, "Heiligtum des Mithras-Kults in Kempraten SG entdeckt", 10 March 2016. "The Mithraeum, used in the 3-4th c. AD and now rediscovered, was a rectangular building with mortared foundation walls and a wooden superstructure, with a shingled roof. It stood away from the village, directly on the lake-side. ... Numerous ceramic and soapstone fragments have been found, which originate from use in cult banquets. Animal bones discovered show that poultry especially was eaten. Further evidence of the cult found are rock crystals, boar tusks, clay balls, and many coins. The stone altar fragments are inscribed, and there is part of a sandstone cult image of a larger-than-life Mithras. The finds will now be cleaned, labelled, inventoried, and carefully packaged. The goal is a scholarly evaluation and publication."

Update 2020:

• Sarah Lo Russo, Regula Ackermann, Hannes Flück, and Markus Peter, "The Mithraeum at Kempraten (CH) – Preliminary Results from a New Discovery in 2015/16", Acta Antiqua Academiae Scientiarum Hungaricae 58 (2018), 199–215. DOI: https://doi.org/10.1556/068.2018.58.1-4.12. Link to journal page here. The article contains plans of the various phases of the Mithraeum, but does not publish the inscriptions.