"The iron pillar of Delhi, India, is a 7m (23 ft) high pillar in the Qutb complex, notable for the composition of the metals used in its construction.
The pillar, which weighs more than six tons, is said to have been fashioned at the time of Chandragupta Vikramaditya (375–413), though other authorities give dates as early as 912 BCE. The pillar is 98% pure wrought iron and is a testament to the skill of ancient Indian blacksmiths. It has attracted the attention of both archaeologists and metallurgists, as it has withstood corrosion for over 1,600 years in the open air."
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