15. The Iron Pillar of Delhi’s Rust Resistance
Standing for over 1,600 years, the Iron Pillar of Delhi has astounded experts with its remarkable resistance to rust. Crafted during ancient times, the pillar’s unique metallurgical composition has withstood the elements far better than many modern alloys.
Despite extensive study, scientists have yet to fully replicate the ancient technique that gave this iron monument its enduring strength.
Source
