To the south of Obernburg a watchtower was discovered by the Reichslimeskommission at the Main, east of the Karlshöhe. Today, this is no longer visible in the terrain. The left bank of the Main is extremely narrow at this point, while on the other side there is a broad area around Erlenbach. A further possible watchtower south of the tower already mentioned was disputed by W. Conrady, as no Roman pottery has been found there. The experienced excavator Conrady described the stonework as "un-Roman". The building is definitely not a watchtower. It can be assumed that along there were watchtowers along the Main, similar to those on land, that watched over enemy territory. To date, however, only one tower has definitely been identified.
"Wachtposten (Wachtturm, Limesturm)", Limes-Lexikon 2009, 135f.
Bavarian State Conservation Office – Landesstelle für die nichtstaatlichen Museen & Bavarian State Archaeological Collection with the support of the Bayerische Sparkassenstiftung