For centuries, visitors to the Qutub complex stood with their backs to the iron pillar and tried to clasp their hands around it for luck. In 1997 the pillar had to be fenced off, to protect it from them
The game was simple, and everybody played it.
You stood with your back against the iron pillar in the courtyard of the Qutub complex in Delhi, reached your arms backwards around it, and tried to make your fingers meet. If they touched, you were lucky.
Millions of people did it, for generations. Palms, sweat, oil, friction, year after year, at the same height on the same iron.
In 1997 a fence went up around the pillar. The monument that had stood in the open air for sixteen centuries without rusting had begun to show damage, and the cause was not the weather. It was us.
Sixteen centuries of weather did nothing. A few generations of affectionate hands did.
The thing itself
The pillar is about 7.2 metres tall from the top of its capital to the bottom of its base, with a little over a metre of that buried below ground. It weighs more than six tonnes. It is made of wrought iron, around 98 per cent pure, and it was not cast in one piece: it was built up by forge welding, by heating and hammering lumps of iron together until they became one shaft.
Think about that for a moment. Six tonnes of iron, joined by hand, hammer and fire, straight enough and sound enough to still be standing.
On its surface is an inscription in Sanskrit, in the Brahmi script of the Gupta period, recording that the pillar was raised as a standard in honour of Vishnu, in memory of a king called Chandra. Most historians identify him with Chandragupta II, which places the pillar around the fifth century.
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Why it does not rust
For a long time this was treated as an unexplained wonder. European scientists who came out to colonial India were puzzled by it, and the question drew serious study from the early twentieth century onwards.
The modern explanation comes largely from the work of the metallurgist R. Balasubramaniam of IIT Kanpur, who studied the pillar over many years and published his findings in Current Science.
The heart of it is phosphorus. The iron in the pillar contains far more phosphorus than modern wrought iron does, because of how it was made. Ancient Indian smiths smelted iron with charcoal and did not add lime, and lime, which modern furnaces use, carries most of the phosphorus away into the slag.
Left in the metal, that phosphorus does something useful. As the pillar goes through cycles of humid and dry weather, it helps form a very thin, even, tightly stuck layer on the surface: a film of iron oxyhydroxide and iron phosphates, one form of which is called misawite. That film is not ordinary flaky rust. It seals the metal beneath it and stops the reaction going any further.
Delhi’s climate helps. The air is dry for much of the year, and dry air is kind to iron.
The film is not ordinary rust. It seals the metal beneath it and stops the reaction going further.
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So where is the mystery?
Not, honestly, in the chemistry. The pillar does not break any law of nature, and it is not the only object of its kind: other old Indian iron pillars and cannons show the same resistance, which suggests a whole tradition of smiths who knew what they were doing.
The real open questions are historical.
We do not know for certain where the pillar first stood. Balasubramaniam argued that it was originally raised at Udayagiri, near Vidisha in Madhya Pradesh, in front of a Vishnu temple, and moved to Delhi centuries later. If so, somebody hauled six tonnes of iron across hundreds of kilometres, and nobody wrote down how.
We do not know exactly how the smiths managed the forge welding at that scale, with that consistency, or how many of them it took.
And we do not know why the technique did not spread and continue as a matter of course, so that iron of this quality became ordinary.
The dent
There is a dent on the pillar. The story attached to it is that a cannonball was fired at it at close range, in the eighteenth century, and failed to break it.
Whether or not that is exactly what happened, the marks on the pillar tell you how people have treated it: something to test, to touch, to wish on, to shoot at, to explain.
It has survived all of it. Cannon, monsoons, conquerors, and finally the fence that had to be built because too many of us wanted to put our arms around a piece of fifth-century iron and feel our fingers meet.
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If you think you have remembered everything about this topic take this QUIZ
Results
#1. Where is the ancient rustless iron pillar located?
#2. According to the text, which historical period is known as the “Golden Age of India” during which the pillar was built?
#3. What is the approximate weight of the iron pillar?
#4. Which specific element was intentionally left in the iron by ancient blacksmiths to help prevent rust?
#5. What is the name of the microscopic protective film that forms on the pillar to stop the rusting process?
#6. Why did the government erect a fence around the pillar in 1997?
#7. How did ancient Indian blacksmiths process the metal to create the massive column?
#8. How much of the pillar’s total length is buried underground to keep it upright?
Why doesn’t the Delhi iron pillar rust?
It refuses to rust because its unusually high phosphorus content reacts with the environment to form a microscopic, highly protective chemical layer called “misawite,” which acts as a permanent shield against moisture and oxygen.
Who actually built the iron pillar?
Historical inscriptions on the pillar in the Brahmi script point to King Chandragupta II of the powerful Gupta Empire, making the pillar over 1,600 years old.
Was the pillar originally built in Delhi?
No, it is widely believed that the pillar was originally erected in front of a massive Vishnu temple in Udayagiri, Madhya Pradesh, and was later moved to Delhi by subsequent rulers as a glorious trophy.
Can tourists still touch the pillar today?
No, for many decades tourists could touch and hug the pillar, but a protective fence was installed in 1997 because the constant rubbing from human hands was beginning to damage the protective chemical layer.
What is the pillar actually made of?
It is made of incredibly pure wrought iron (about 98% pure) that was manually heated and hammered together using an ancient technique known as forge welding.
Sources & References
R. Balasubramaniam, papers on the Delhi iron pillar in Current Science (1997 onwards) and his book Delhi Iron Pillar: New Insights (2002) — the passive film, the role of phosphorus and slag inclusions, and the argument that the pillar originally stood at Udayagiri.
T. R. Anantharaman, The Rustless Wonder: A Study of the Delhi Iron Pillar (Vigyan Prasar, 1996) — a review of the scientific work on the pillar.
Ancient Origins, “The incredible rust-resistant iron pillar of Delhi” (2020) — the fence of 1997, and the other ancient Indian iron objects with similar corrosion resistance.
CNN Travel, “New Delhi’s iron pillar has been exposed to the elements for 1,600 years” (2024) — the misawite film, the absence of lime, and the account of the cannonball.
