Teudt was particularly interested in the natural stone formation of the Externsteine near Detmold, which he suggested was the location of a central Saxon shrine, the location of Irminsul and an ancient sun observatory. He assumed that the Germanic buildings there had been made from wood and thus left no traces. Teudt was put in charge of the excavations at the site and appointed to head the work done there by the "Reichsarbeitsdienst" in 1934/35. Teudt thought that the Externsteine had served as an observatory until its destruction by Charlemagne. He initiated the demolishing of tourist infrastructure (tramway, hotels) and the creation of a "sacred grove" nearby.