Pyongyang, August 28 (KCNA) -- In Kaesong City, the Democratic People's Republic of Korea, there are Koryo Songgyungwan Academy and Manwoldae, which were listed as world's cultural heritages. The academy, believed to have the longest history in the world, was a top government educational institution in the period of Koryo Kingdom (918-1392). Built in 992, it covers 10 000 square meters, with 18 buildings which give a glimpse of the architectural art in that period. The academy's buildings were reduced to debris by the Japanese invaders during the Imjin Patriotic War (1592-1598) and were rebuilt in the 1602-1610 period. Manwoldae, located in Songak-dong, Kaesong City, is the site of royal palace dating back to the Koryo Kingdom. Founded in 918, Koryo built a royal palace in the site next year. The site breaks into Kungsong with royal palace buildings and Hwangsong with government's buildings. Its total area is 1.25 million square meters, 390 000 square meters of which belong to Kungsong. The main gate of Hwangsong is Kwanghwamun in the east and the main gate of Kungsong is Sungphyongmun in the south.