Final answer:
The Great Wall of China was significantly enhanced during the Ming Dynasty, resulting in a fortification that stretches approximately 1,550 miles by the 16th century BC.
Step-by-step explanation:
By the 16th century BC, the Great Wall of China stretches about 1,550 miles. This great fortification was enhanced and extended during the Ming Dynasty to protect the capital of Beijing and the agricultural heartland of Liaodong Province. While the Great Wall is often thought to be visible from space, this is a myth, as China's first astronaut confirmed upon his return to Earth. The reality of the Wall's existence is more complex; it consists of many walls built at different times, not always with a coherent singular purpose in mind. The Long Walls built since the early empire were improved upon by the Mings, and it is thanks to their tremendous efforts that the Wall became a formidable defense system.