Gongju was once called Ungjin, and for sixty-odd years in the fifth and sixth centuries it was the capital of the kingdom of Baekje, when the court fled south after Goguryeo armies destroyed its first capital near modern Seoul. The fortress of Gongsanseong stands on a ridge above the Geum river, with the town spread out below, and its walls, over two kilometres long, follow the contours of the hill. Much of the stone you walk along dates to a rebuilding in the Joseon period, but the site itself is Baekje, and so is the feeling of a defendable high ground with a wide river as its moat.
The fortress has one famous refugee from a later era. In 1624, King Injo fled here from a rebellion in Seoul and stayed for a few days, and he is said to have rewarded a tree for sheltering him. You can walk the full circuit in an hour or so, with views over the river and the town, and the pavilion of Gongbukru stands near the north gate. Archaeologists have found the royal palace area on the ridge, but the real treasures came from a tomb nearby: the burial of King Muryeong, which was found intact in 1971 with its gold ornaments, and is the best-preserved royal tomb of the kingdom. The Baekje sites here and at Buyeo and Iksan were listed as World Heritage in 2015.
For motorcycling, South Korea is a country of mountains and cameras, and the roads around Gongju are no exception. The Geum river valley is gentle, and the nearby Gyeryongsan National Park offers forest roads, temples and granite peaks. Speed cameras are everywhere, announced with big signs, and they are enforced, so keep to the limits. Rural roads have a good surface and clear signs in Korean and English. Autumn is the highlight, when the maples and ginkgoes turn gold and red, and the countryside is full of drying persimmons and harvested rice fields.
Gongju has about seventy thousand people, so it has plenty of fuel stations, restaurants and places to stay. The town is known for its chestnuts, which turn up in cakes, bread and rice dishes, and a bowl of chestnut makgeolli, the milky rice wine, goes down well after a day in the saddle. Winter can be cold and icy, and summer is humid, with a monsoon in July, so spring and autumn are best.