Only few sources from the time the Sommerpalais was built are available today. It is nonetheless certain that the architectural elements originate from the late 1770s. A memorial plaque from June 1, 1779 states: »Der regierende Fürst Heinrich XI. läßt das Sommerpalais ausbauen und mit Stuckarbeiten, Tapeten etc. schmücken« (The ruling Prince Heinrich XI has the Sommerpalais adorned with stucco, wallpapers etc.).