The Buyeo National Research Institute of Cultural Heritage published Busosanseong Fortress 1981-2002, a book compiling the excavation results of the Busosanseong Fortress in Buyeo, South Chungcheong Province from 1981 to 2002, on the 40th anniversary of the research. The book is a bundle of seven reports on the excavation of Busosanseong Fortress previously released by the NRICH and the Buyeo National Research Institute of Cultural Heritage with photos and drawings newly converted into high-resolution color and digital images. In the book, the ruins of the Baekje era castle are largely divided into the fortress and the sites inside the castle. Fortress ruins include traces of gates and affiliated facilities while building sites, water system and other facilities were found inside the castle. The book also marks the exact site of the protective structure built for the Monument for Liu Renyuan of Tang China, which was destroyed during the Japanese colonial rule and moved to the Buyeo National Museum after Korea’s liberation.