The castle is not mentioned in a document, so its year of construction can only be estimated. In 1388, Strahlegg Castle served as an outpost against the Confederates in the Näfels war between Austria and Habsburg and was therefore conquered and destroyed by the Glarnern. [1]
The first excavation took place in August 1861. Ferdinand Keller determined that it must be a medieval castle. Later, Roman ceramic fragments were found during explorations. Overall, however, the complex could not be dated. A careful archaeological investigation was not carried out until 1960. It was found that it must have been a Roman watchtower, which was built in 15 BC. Was built under the Roman emperor Augustus. There is a line of sight to two other watchtowers; the first in the hamlet of Voremwald near Filzbach am Kerenzerberg, the second on the Biberlichopf near Ziegelbrücke. It was found that part of the masonry dates from the Middle Ages, so the ruined Roman tower was rebuilt at that time.
The tower has a square floor plan with a side length of 10.4 by 10.4 meters. There is still a 6 meter high masonry made of stored, roughly hewn limestone. Medieval masonry can only be found at the top on the west wall. The foundation is separated inside and outside by six neatly executed paragraphs. The uppermost paragraph lies on the inside above the former beam position. There are beam holes on all four sides, whereby probably only the holes in the north and south walls seem to have received a layer of beams, the others seem to have been used for an external battlement. The entrance is on the south side, where the wall was broken out.