Iron pillar of Delhi
The iron pillar of Delhi is a structure 7.21 metres (23 feet 8 inches) high with a 41-centimetre (16 in) diameter that was constructed by Chandragupta II (reigned c. 375–415 CE), and now stands in the Qutb complex at Mehrauli in Delhi, India.[1][2] It is famous for the rust-resistant composition of the metals used in its construction. The pillar weighs more than 6 tonnes and is thought to have been erected elsewhere, perhaps outside the Udayagiri Caves,[3] and moved to its present location by Anangpal Tomar in 11th century.
The height of the pillar, from the top to the bottom of its base, is 7.21 m (23 ft 8 in), 1.12 m (3 ft 8 in) of which is below ground. Its bell pattern capital is 306 mm (12 in). It is estimated to weigh more than six tonnes (13,228 lb).[4] The pillar has attracted the attention of archaeologists and materials scientists because of its high resistance to corrosion and has been called a "testimony to the high level of skill achieved by the ancient Indian iron smiths in the extraction and processing of iron".[5][6] The corrosion resistance results from an even layer of crystalline iron(III) hydrogen phosphate hydrate forming on the high-phosphorus-content iron, which serves to protect it from the effects of the Delhi climate.[5]
The pillar carries a number of inscriptions of different dates, some of which have not been studied systematically despite the pillar's prominent location and easy access.[citation needed ]
