The ancient structure that served as a tomb for the Persian king Darius I is known as the **Darius' Tomb at Naqsh-e Rustam**. Located near the ancient city of Persepolis, this rock-cut tomb showcases the grandeur of Achaemenid architecture. The site is notable for its impressive reliefs and inscriptions that reflect the king's power and divine sanction. Darius I, who reigned from 522 to 486 BCE, was an important figure in Persian history, known for his administrative reforms and expansive empire, making his tomb a significant archaeological and historical landmark.