The Haga Echo Temple was built in 1790 as a summer dining room for Gustav III who loved to dine outdoors. It is situated in Hagaparken in Solna just north of Stockholm. The architect was Carl Christoffer Gjörwell.
Wikipedia https://en.wikipedia.org/wiki/Haga_Echo_Temple
Address (Unnamed Road), Sweden
Coordinates 59°21'45.832" N 18°2'28.586" E