Remember Mainz during the era of formidable fortresses? Today we are standing before the Hauptstein Cavalier. It is a testament to Mainz’s strategic importance. This is not just another old building. The Hauptstein Cavalier embodies centuries of military history.
Let’s rewind to 1633. Swedish forces occupied Mainz. They built the first fortifications here. This early earthwork resembled those on Albansberg and Jakobsberg. It marked one of Mainz’s oldest defensive sites. Matthäus Merian’s copper engraving depicts a citadel with ravelins. These protected its flanks. Initially the Hauptstein site lacked permanent structures. Only wooden huts stood here. After Mainz was retaken the fortification fell into disrepair.
Almost a century passed. Elector Lothar Franz von Schönborn expanded Mainz’s fortifications. He constructed walled sconces. Plans from that time referred to the site as “Fort St. Francois”. Fort Hauptstein’s Kehlreduit was designed by master builder Maximilian von Welsch. Its construction began around 1713. Forts Karl and Joseph were built simultaneously. The cellar of Hauptstein’s Kehlreduit remains the only one still visible above ground.
Mainz became a Federal Fortress. Reinforcements were required. Wooden blockhouses on the Kehlreduits of Forts Karl, Joseph, and Hauptstein were removed. Stone upper floors replaced them from 1842.
Under the German Empire, around 1873, expansion led to the creation of the Rheingauwall. The Franziskus-Schanze became the Hauptstein Cavalier. It integrated into the defense line between Fort Joseph and Cavalier Prinz Holstein. The military transformed the adjacent Kehlreduit into a war laboratory. They sealed loopholes facing the outer field and closed access to mine passages.
Fortunately the structures survived the post-1900 disarmament. They transitioned to civilian use. Initially it served as a homeless shelter. During World War II, it may have been a POW camp. Later, it became emergency housing for refugees. The last families vacated the building around 1960. The planned construction of the Taubertsbergbad nearly resulted in its demolition. Yet it narrowly escaped destruction. From the 1970s, local clubs adopted it as their clubhouse.
The two structures on the Hauptstein showcase three distinct construction phases. They create a unique ensemble. It represents Mainz’s fortress history spanning over 300 years.
You can see that the buildings have been renovated since 2021. They will soon be a worthy part of the cityscape again. While public access inside is restricted, the Cavalier’s facade is visible. The Kehlreduit is fenced, but partially viewable from the street. The rear of both buildings can be seen from the adjacent open-air bath’s lawn. The Hauptstein Cavalier silently watches over the city.