The seal tower, built in 1545, is the distinctive landmark of Diessenhofen, in which seals and documents were kept. The tower is adorned with a clock with the 12 astrological symbols and a moon clock that shows the respective phase of the earth's satellite.
The origins of the settlement go back to the Stone and Bronze Ages, as evidenced by individual finds in the shallow depressions of the district and on the banks of the Rhine. A coin treasure from Roman times is dated from 251 to 270. Remains of three watchtowers of the Danube-Iller-Rhein-Limes date from the 4th century.