The Iron Pillar of Delhi
In Delhi stands an iron pillar more than 1,600 years old, and it has barely rusted.
What was reported
In the courtyard of the Qutb complex in Delhi stands a pillar of solid iron about 7 metres tall. An inscription on it, from the Gupta period, honours a king named Chandra, thought to be Chandragupta II, who ruled around 1,600 years ago.
Despite standing in the open through centuries of monsoons, it shows very little rust. Visitors used to try to wrap their arms around it backwards for luck, and it is now fenced off to protect it.
Explanations offered
Metallurgists, including R. Balasubramaniam of IIT Kanpur, found that the iron contains a high level of phosphorus and very little sulphur. Over time, this formed a thin protective layer on the surface that slows rusting. It is a mark of the skill of ancient Indian ironworkers, not a mystery of physics.
- When
- About 1,600 years old
- Where
- Qutb complex, Mehrauli, Delhi, India
- Witnesses
- Visitors every day
- Status
- Explained
Famous cases are real, widely reported events. Each file sets out what witnesses said and the explanations that have been offered, without taking a side.