长城(cháng chéng) - Great Wall in Mandarin

长城 (Chángchéng) is the Great Wall, the chain of fortifications that snakes across northern China for thousands of kilometres. 长 (cháng) means "long" and 城 (chéng) means "city wall" or "town", so the name is simply "long wall".

It was never a single continuous build: different dynasties added, rebuilt and abandoned sections over roughly two thousand years, which is why the wall near Beijing looks so different from the crumbling earth ramparts further west. The most-visited stretches, 八达岭 (Bādálǐng) and 慕田峪 (Mùtiányù), have been heavily restored for tourists.

There is a well-known saying, 不到长城非好汉 (bú dào Chángchéng fēi hǎohàn), "if you haven't been to the Great Wall you're not a true hero", which is worth learning alongside the word itself since it turns up constantly in guidebooks and on souvenir T-shirts.