The Ondal Fortress (Hanja: 溫達山城) is a Goguryeo-era fortress, located at Hari san 67-beonji, Yeongchun-myeon, Danyang County, Northern Chungcheong Province. This fortress is also known as Euradan Fortress (을아단산성/乙阿旦山城) and bestowed from Goguryeo General during the reign of King PyeongWon, General Ondal the Fool.
The fortress has been preserved in its original form throughout some 1,400 years and shows the advanced building skills of Goguryeo Era (37 BC-668 AD). Although this fortress is only 683 meters long and 7 meters tall, it was enough to fend off the enemy army. It’s particularly because the steep mountain made it harder for the enemy to approach. The hill is now covered with wild flowers and pine trees but in the past, there was a well inside the fortress, providing ample drinking water to the soldiers. A number of bowls were also discovered around the well. Most likely, it was where they used to cook. Records indicate that while soldiers went about their daily life inside the fortress, invading soldiers got too tired and gave up invading.
The wall is made of layers of granite slabs. No clay was used, but it’s still very solid and there was no worry of collapsing because all the crevices were filled with small stones. The slabs on the outside and those on the inside were stacked over each other to make the wall more solid. That’s why most of the wall except the portion near to the river is still intact even after 1,500 years.
The annual Ondal Culture Festival is held every October around Ondal Cave and Ondal Fortress in memory of the legendary love story between General Ondal the Fool and Tear-jerking Princess Pyeonggang. Other attractions in the area include a theme park and Jangseung (Korean traditional totem poles) Park.