The Great Wall of China is one of the most famous structures in the world. It was built over 2,000 years ago during the Qin Dynasty to protect China from invaders. The wall stretches for over 13,000 miles across northern China. It is made up of brick, wood, and stone and was built by soldiers, peasants, and prisoners. Although it was never fully successful at keeping invaders out, the Great Wall is still an important symbol of China's strength and determination.
Which detail from the passage supports the idea that the Great Wall of China was a massive project?