Name of the former summer palace of Frederick the Great, King of Prussia, in Potsdam (4,5)
I believe the answer is:
sans souci
(Other definitions for sans souci that I've seen before include "Frederick the Great's Potsdam palace" , "lack of care" , "Without care or worry (Fr.); Frederick the Great's palace" , "Potsdam palace built by Frederick the Great" , "Prussian palace" .)