Final answer:
Ramses the Great's main achievement was expanding Egypt's borders and ruling for 66 years.
Step-by-step explanation:
Ramses the Great's main achievement was expanding Egypt's borders and ruling for 66 years. He is known for his military campaigns and successful conquests, which led to the largest territorial extent of the Egyptian Empire. His reign also witnessed remarkable architectural accomplishments, with many temples and monuments built during his rule, including the famous Abu Simbel temples.
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