The structure known as the longest wall in the world is the Great Wall of China. This ancient fortification was built over several dynasties, primarily during the Ming Dynasty, for defense against invasions and raids. The Great Wall stretches over 13,000 miles and traverses various terrains, including mountains, deserts, and grasslands. Construction began as early as the 7th century BC, showcasing the ingenuity and perseverance of Chinese workers through the centuries. The wall not only served a military purpose but also symbolized the strength and unity of the Chinese nation. It remains a significant cultural and historical landmark today.