The fortification, the Burgus, is presumably a three-story tower with a ground area of about 20 x 13 meters, surrounded by a deep ditch a few meters away. The massive stone tower has walls up to three meters thick and was referred to in the Middle Ages as "domus fortis supra Lonetam" - strong house on the Lahn. This eventually leads to the today's name of the city of Lahnstein. When the Romans abandoned the Rhine Valley in the 5th century, the Burgus lost its military significance. It was subsequently used as a residential fortress. In 1549, it is mentioned for the last time in a document; at that time, it is just a ruin. It wasn't until 1914 that the Roman fortification was rediscovered. Extensive excavations uncovered it in 1926. To conserve this significant cultural monument, the excavation was covered again in 1946 with bomb rubble from World War II. Since then, the Roman Burgus has been waiting for further research.