The Great Wall of China is a UNESCO World Heritage Site and one of the most popular tourist destinations in the world. It is a symbol of China's rich history and culture. The Great Wall is a massive structure, stretching over 6,000 kilometers from east to west. It was built over a period of many centuries, beginning in the 7th century BC. The Great Wall is made of stone, brick, and earth. It is an impressive feat of engineering and a testament to the ingenuity of the Chinese people.