Interesting fact:

One of the most famous walls of all time is The Great Wall of China. It’s the longest human-built structure. It stretches for more than 6400 km and dates back to the 5th century BC when the first part of it was constructed. It served as a border control and as protection from anyone who would come from the North. The defensive mechanism of the Great Wall is recognized as one of the best in the whole world. It’s one of the New Seven Wonders of the World.