Answer: Approximately 13,000-15,000 miles.
Explanation: The Ming Dynasty was a period of prosperity in China. In this era, the Great Wall of China was rebuilt, and the focus was to strengthen and fortify against invasions (mainly from Mongols at the time). By the end of the Ming Dynasty, the Great Wall of China stretched approximately 13,000-15,000 miles. This converts to 21,000 kilometers.
