#7: The Iron Pillar of Delhi and Its Resistance to Rust
Standing for over 1,600 years, the Iron Pillar has resisted corrosion despite exposure to weather. Its composition includes a high phosphorus content that contributes to a protective oxide layer. The forging techniques used to create such a large, stable structure remain impressive even by modern standards. It serves as a quiet testament to advanced metallurgical knowledge in ancient India.
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