Laoniuwan Dun is located on the north side of Laoniuwan Fort, is a hollow masonry tower, and is an important military defense facility in the old fort, has been called "the first Dun in the world". There is a plaque on the forehead of the south gate, engraved with the four characters of "Lao Niu Wan Dun" in regular script, and there is a title and a signature, with the Chinese words of the 25th year of Wanli of Ming Dynasty (AD 1597). The Dun is 12 meters high, and there are rope ladders and passages for soldiers to go up and down inside the Dun. There is a machicolation on the Dun, which is used to watch the enemy's situation on the opposite side of the Yellow River, and can light smoke to transmit military information to the Great Wall on the east and south sides. Now this well-preserved Dun has become a landmark building in Laoniuwan Scenic Area.
