This pillar stands in the courtyard of the Jama Masjid but it has been there since long before the mosque's construction. A six - line Sanskrit inscription indicates that it was initially erected outside a Vishnu temple, and was raised in memory of the Gupta King Chandragupta Vikramaditya. This is a seven-metre-high pillar. What the inscription does not tell is how it was made. Scientists have never discovered how this iron, which is of such purity that it has not rusted after 2000 years, could be cast with the technology of the time. It?s a wonder.