Koryo ceramics began to be produced in the 10th century and attained the highest stage of their development in the period of the 11th-12th century. They were glazed in blue, black, white or red colours.
The jaded green celadon was the most beautiful and renowned; it was the symbol of Koryo ceramics. Koryo ceramics have been widely known as the finest of their kinds in the world.
The 37th session of the UNESCO World Heritage Committee held in Phnom Penh, Cambodia, on June 23, 2013 decided to inscribe a number of historical remains in Kaesong in the list of world cultural heritage.
They include the Mausoleum of King Wang Kon, Mausoleum of King Kyonghyo, Nam Gate, Walled City of Kaesong, Sungyang Confucian School, Phyochung Monuments, Sonjuk Bridge, Koryo Songgyungwan, Manwoltae, astronomical observatory Chomsongdae in Kaesong, Seven Tombs Cluster and Myongrung Cluster.