The present viewing platform of the Rheinkavalier was used in 1609 as a bastion of the electoral city wall. Its task was to protect the expanded Rhine port and the Rhine crane, which still exists today as a gauging station. Furthermore, the building was equipped with an icebreaker with hump blocks that protected ships and the harbour. When at the end of the 19th century the Prussian city wall was demolished and the Rhine facilities extended, the cavalier was partially demolished. After the port was relocated to the Moselle, it was converted into a viewing platform. After the Second World War the cavalier was rebuilt again.