Renowned for 'the Great Wall Museum in the open air', Shandan Great Walls are the best-preserved ancient wall in China. Built in the Han (260 BC - 220) and Ming (1368 - 1644) Dynasties, they are two parallel walls going at the same direction for about 200 km (124 miles) in Shandan County. Along the walls, there are also an ancient post house built in the Ming Dynasty and a Great Wall Museum displaying the cultural relics.