Tiger Mountain, a short, steep, and impeccably restored section of the Great Wall located 30km (19 miles) northeast of Dandong, forms part of China's border with North Korea. A brief hike along the Wall provides beautiful views of surrounding cornfields, and the return path takes you right up against the small stream that separates Chinese and North Korean territory. South Chinese sometimes wander onto stones set in the stream just behind the Wall to trade goods and information with North Korean soldiers and farmers. Warning: Cross over on the stones yourself and you risk arrest.