VisitKorea @ KoreanTravel Guess where the mysterious forest in " The King : Eternal Monarch " is located ! It ' s in Busan and it ' s called Ahopsan Forest . The forest is a popular filming location ! Ahopsan Forest ( # 아홉 산 숲 ) 37 - 1 , Midong - gil Cheolma - myeon , Gijang - gun , Busan