Schloss Petersaue

Near his secondary residence, Schloss Johannisburg in Aschaffenburg, he created the Schönbusch Palace with one of the first English landscape gardens of Germany.

[1] Behind the charterhouse with view on Mainz, he constructed a one-storey maison de plaisance in neoclassical style.

The Portuguese architect Emanuel Joseph von Herigoyen (1746-1817) could be a possibility as he designed various buildings for the Prince-elector in Aschaffenburg and Schönbusch.

They decided to significantly enlarge the Fortress of Mainz, and strongly fortified the island of Petersaue.

Also, there is a painting with a view of Mainz by Christian Georg Schütz showing the Electoral palace of Petersaue.

View of Mainz from the Rhine Isle of Petersaue with the Electoral Summer Palace by Christian Georg Schütz around 1786 (State Gallery Schloss Johannisberg - Kurmainzische Galerie, Inv. Nr. 6569)
Friedrich Karl Joseph von Erthal
Map of the Rhine Isle of Petersaue of 1798 showing the location of the Electoral Palace right above and the fortifications created by the French