The Great Wall

Around 220 BC, Qin Shi Huang linked older frontier fortifications into a single defensive line against raids from the north — the beginning of the Great Wall. Rebuilt and extended for centuries, above all under the Ming dynasty between 1368 and 1644, it grew into the largest military structure ever raised, striding across mountains, deserts and grasslands. UNESCO placed the Great Wall on the World Heritage List in 1987.