Kaesong, 125 miles to the south of Pyongyang, has various historical remains and relics. It was the capital of Kouryo, the first unified state of the Korean peninsula (918-1392). The royal palace of Kouryo, the "Mangweuldai", is on the site of Mount Song-Ak, in the middle of a luxuriant pine forest. The museum of Kouryo is also here, it was an establishment for the school of Confucianism, and has several precious remains. The Tcheumseung observatory was already being used at the time. Mount Djanam, in the beautiful centre of the town, has picturesque scenery that has been famous since ancient times. The town is mostly known for "Insam Kouryo", the ginseng whose pharmaceutical properties are famous. Due to the specific ground, water, climate, methods of cultivation and transformation, this is the medicinal plant of the region par excellence. It is classified as a toner, for combating fatigue, and providing vigour and good health. It also provides longevity. In the suburbs, a 740-acre vineyard provides the Sariwon wine. The artistic speciality of the region is pottery. The famous celadon-porcelain of Kouryo is pale green or jade blue. The pieces are real works of art, and famous for their decorative models.