Despite being 1600 years old, this seven-metre high pillar has never rusted. It was made during the reign of Chandragupta II (reigned about 375–415) – we know this because the lack of rusting has resulted in the inscription remaining clear and readable.

Scientists and archaeologists have been intrigued by why it’s never rusted. It’s generally put down to high quality of the iron smiths who made it, although it may also have developed a thin protective coating over the centuries. What’s more certain is that it’s not always been on this spot – and although nobody is sure about where it previously stood, the best guess is that it was moved to its present site around 800-900 years ago. 

For me this is yet another great example of where history and science meet. When we interpret historical objects, we have to do so fairly, presenting our evidence for why we say what we say. And we also have to acknowledge that when historical sources and scientific analysis can only get us so far. Some things remain mysteries that future generations can have a go at solving.