Case file · Folklore / legend
The rustless Iron Pillar of Delhi
The seven-metre iron pillar at the Qutb complex, erected around 400 CE under the Gupta king Chandragupta II, has hardly rusted in 1,600 years, inspiring claims of lost or alien metallurgy.
402 CE · 28.52, 77.19 · status: explained
The sceptical view
Metallurgists at IIT Kanpur showed high phosphorus content and a protective film of misawite form a passive layer, helped by Delhi's dry climate.