Final answer:
Alexander The Great's longest lasting achievement was the spread of Greek culture.
Step-by-step explanation:
Alexander The Great's longest lasting achievement was the spread of Greek culture. After conquering a vast empire, Alexander actively promoted and disseminated Greek customs, language, and art throughout the lands he ruled. This cultural influence persisted long after his death, as Greek became the language of trade and scholarship in many regions. The Hellenistic civilization, which emerged from the blending of Greek and local cultures, thrived for centuries and left a lasting impact on the world.
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