As early as the 4th century, Saint Castor founded an early Christian community in the district of Karden. The Mosel Cathedral, St. Castor's collegiate church, is dedicated to him. Together with a Romanesque ensemble of monastery buildings that is well worth a look, it bears witness to a lengthy spiritual tradition that can also be discovered in the Treis-Karden Monastery Museum. Treis was the central point of the early medieval Trechirgau district. Even now, the castle ruins can be found in the forest.
The region's history stretches back even further when you head up the mountains: Martberg once attracted Celtic druids and priests of Roman cults. The sanctuary with a panoramic view has been reconstructed in a manner faithful to the original and gives an idea of how deeply religious people were, even in those days.