Final answer:
The Great Wall of China and Hadrian's Wall were both built as defensive fortifications to protect their empires. They were also significant engineering achievements.
Step-by-step explanation:
The Great Wall of China and Hadrian's Wall had several similarities. Firstly, both walls were built as fortifications to protect their respective empires from external threats. The Great Wall of China was built by the Chinese emperors to defend against the Mongol tribes, while Hadrian's Wall was constructed by the Roman emperor Hadrian as a defensive barrier against the tribes of northern Britain. Secondly, both walls were significant feats of engineering. The Great Wall of China is over 13,000 miles long and stretches across different terrains, including mountains and deserts. Similarly, Hadrian's Wall was approximately 74 miles long and included milecastles and guard towers along its length.