A fortress where the touching love story of Goguryeo's General Ondal and Princess Pyeonggang lives on

This fortress was built during the Three Kingdoms period and is 683 meters long, 10 meters high, and 4 meters thick. It is a half-moon-shaped Toemoe-style* castle built on the summit of Seongsan Mountain (427 meters above sea level) and is the best preserved of the stone fortresses. From Ondalsanseong Fortress in Danyang, you can enjoy a spectacular view of the winding Namhangang River, Sobaeksan Mountain, and Taehwasan Mountain. Ondalsanseong Fortress was the scene of fierce battles between Goguryeo and Silla, so it's interesting to imagine standing on the fortress and watching the other side's movements in the distance.
* The term Toemoe-style refers to a form of stacking that goes around the top of a mountain like a band.

In addition to the story of General Ondal's meeting with Princess Pyeonggang, The History of the Three Kingdoms (Kim Bu-sik, 1145) records his last moments as "General Ondal of Goguryeo fought against the Silla army and was killed by an arrow at Adanseong Castle". In Danyang, the Ondal Tourist Park, which includes Ondalsanseong Fortress, Ondaldonggul Cave, and Ondalgwan Museum, was developed around the theme of General Ondal, and the Ondal Culture Festival is held every October.

Inside the castle, artifacts from the Three Kingdoms period, such as tiles and pottery fragments, have been discovered, and the ruins of a well used to collect rainwater remain, and there are trapezoidal drains outside the walls. The style of the southwest gate and the east gate projection part are noteworthy as they are rarely seen in ancient Korean fortresses. There is a limestone cave called Ondaldonggul Cave under the cliffs of Namhangang River northeast of the castle, and there are also several legends related to General Ondal on Taehwasan Mountain to the north.

From the Ondal Tourist Park, you can climb a well-maintained staircase for about 30 minutes to reach Ondalsanseong Fortress, and then continue on a leisurely 12km trek through Bangteo and Sobaeksan Recreational Forest to Goduneomeojae (Bobaljae Hill), a scenic spot for fall foliage. This path is part of the 'Ondal/Pyeonggang Romance Trail', the sixth trail of the 'Sobaeksan Mountain Jarak-gil Trail'.