Great Wall of China

The Great Wall of China is a series of fortifications made of stone, brick, tamped earth, wood, and other materials, generally built along an east-to-west line across the historical northern borders of China in part to protect the Chinese Empire or its prototypical states against intrusions by various nomadic groups or military incursions by various warlike peoples or forces. It is included in lists of the "Seven Medieval Wonders of the World" but was of course not one of the classical Seven Wonders of the World recognized by the ancient Greeks. Even so, it has become a great tourist attraction and finding cheap travel deals is essential. The Wall was made a UNESCO World Heritage Site in 1987.