Iron Pillar of Delhi

Stand still for a moment and listen. Sparrows chatter in the stone arches around you. Feet shuffle across warm, uneven paving. In the middle of this old courtyard rises a smooth, dark column of iron. Its surface is a deep brown, almost chocolate in tone, and in strong sunlight it carries a faint metallic sheen. It looks modest beside the soaring red tower nearby. Yet many people consider this quiet pillar one of the most remarkable objects in all of Delhi.

You are inside the Qutb complex, in the Mehrauli area of south Delhi. The complex is a UNESCO World Heritage Site, and most visitors come for the Qutb Minar, that tall fluted tower of red and buff sandstone. But the Iron Pillar is far older than the minaret. It stood for many centuries before the first stones of the tower were laid. It now sits in the courtyard of the Quwwat-ul-Islam mosque, one of the earliest mosques built in Delhi.

Look at its proportions. The column is roughly seven metres tall, and part of it continues below the ground. It weighs more than six tonnes. At the top sits a decorated capital, shaped a little like a bell, with bands of ribbed and rounded forms. Scholars believe something once stood on that capital — perhaps an emblem connected to the god Vishnu. Whatever it was, it is gone today, and nobody can say for certain what it looked like.

Now lower your eyes to the shaft. On the pillar's surface you can see lines of carved writing. This is the oldest inscription on the column, written in Sanskrit, in an early form of the Brahmi script. Brahmi is the ancestor of many writing systems across South and Southeast Asia. The verses praise a powerful king named Chandra. They describe his victories and say that the pillar was raised as a standard, or banner, of Vishnu.

Who was this Chandra? Most historians identify him with Chandragupta the Second, a ruler of the Gupta dynasty. The Guptas governed much of northern India around the fourth and fifth centuries of the Common Era. Many people call this period a golden age for Indian science, art and literature. Mathematics, astronomy and Sanskrit poetry all flourished. So when you look at this pillar, you are looking at metalwork from roughly sixteen hundred years ago.

Here is the first surprise. The pillar almost certainly did not begin its life in Delhi. The inscription says it stood on a hill called Vishnupada, which means the footprint of Vishnu. Scholars still debate where that hill was. Some point to sites in central India, such as Udayagiri, near the city of Vidisha. How and when the column travelled here is also uncertain. Later inscriptions on the shaft suggest that it had arrived in this area by the medieval period.

Now for the detail that brings scientists here from around the world. Iron left outdoors usually rusts, flakes and eventually crumbles. This pillar has stood in the open air for well over a thousand years. Monsoon rains have fallen on it, and summer heat has baked it. Yet its main surface shows remarkably little rust. For a long time, this puzzle produced wild theories. Some people even claimed it was made from some lost or mysterious metal.

The real answer is more interesting than any myth. Metallurgists, including researchers at the Indian Institute of Technology in Kanpur, studied the iron closely. They found that it contains an unusually high amount of phosphorus. Over time, this helped a thin protective layer form on the surface. That layer slows down further corrosion. Delhi's fairly dry climate also helps. In short, the pillar resists rust because of the way it was made, combined with the place where it stands.

Think, too, about how it was made. There were no giant furnaces capable of pouring a single six-tonne casting. Instead, the smiths most likely heated lumps of iron and hammered them together, piece by piece. This process is called forge welding. Imagine the heat, the sparks, and the rhythm of many hammers working over a long period. Producing a column this large and this even was a major achievement of ancient craftsmanship.

Now look at the low fence around the base. It has a story too. For generations, a popular tradition said that if you stood with your back to the pillar and wrapped your arms around it, your wish would come true. Crowds tried it every day. All those hands, rubbing and gripping, wore down and discoloured the lower part of the column. So the authorities put up the fence to protect it. You may still notice that the lower section looks slightly different from the rest.

There is one more tale people often tell here. Near the middle of the shaft, some visitors point to a mark or dent. A popular story says that it came from a cannon ball fired during a later invasion. This is local lore rather than documented history, so treat it as a story. Still, it shows how the pillar has gathered legends over the centuries, like a piece of driftwood gathering shells.

Step back and take in the setting. Around you stand rows of carved stone columns. Many of them came from older Hindu and Jain temples, and the builders of the mosque reused them. Look closely at the columns and you can see bells, garlands and floral patterns carved into the stone. Above you rise the great arched screens of the mosque, covered in flowing calligraphy and vine patterns. Different faiths, rulers and centuries meet in this one courtyard.

That layering is perhaps the real lesson of the place. A Gupta king raised the pillar in honour of Vishnu. Later rulers moved it, carved their own names on it, and built a mosque around it. Then the tower rose beside it. Today visitors from every corner of the world gather here, phones raised, reading the same weathered letters. The pillar has outlasted every one of those empires, and it has barely rusted.

Before you move on, look at the iron one more time. Notice how the light shifts across its surface as clouds pass overhead. Notice the hum of voices, the call of birds in the arches, and the warmth rising from the stone under your feet. This column has watched this courtyard for more than a thousand years. As you walk away toward the tower, glance back once. It will still be standing there, dark and steady, long after today's crowds have gone home.