text: The pillar was installed as a trophy in building the Quwwat-ul-Islam mosque and the Qutb complex by Sultan Iltutmish in the 13th century. Its original location, whether on the site itself or from elsewhere, is debated.
  According to the inscription of king Chandra, the pillar was erected at Vishnupadagiri (Vishnupada). J. F. Fleet (1898) identified this place with Mathura, because of its proximity to Delhi (the find spot of the inscription) and the citys reputation as a Vaishnavite pilgrimage centre. However, archaeological evidence indicates that during the Gupta period, Mathura was a major centre of Buddhism, although Vaishnavism may have existed there. Moreover, Mathura lies in plains, and only contains some small hillocks and mounds: there is no true giri' (hill) in Mathura.
  Based on paleographic similarity to the dated inscriptions from Udayagiri, the Gupta-era iconography, analysis of metallurgy and other evidence, Meera Dass and R. Balasubramaniam (2004) theorized that the iron pillar was originally erected at Udayagiri. According to them, the pillar, with a wheel or discus at the top, was originally located at the Udayagiri Caves. This conclusion was partly based on the fact that the inscription mentions Vishnupada-giri (IAST: Viṣṇupadagiri, meaning "hill with footprint of Viṣṇu"). This conclusion was endorsed and elaborated by Michael D. Willis in his The Archaeology of Hindu Ritual, published in 2009.
  The key point in favour of placing the iron pillar at Udayagiri is that this site was closely associated with Chandragupta and the worship of Vishnu in the Gupta period. In addition, there are well-established traditions of mining and working iron in central India, documented particularly by the iron pillar at Dhar and local place names like Lohapura and Lohangī Pīr (see Vidisha). The king of Delhi, Iltutmish, is known to have attacked and sacked Vidisha in the thirteenth century and this would have given him an opportunity to remove the pillar as a trophy to Delhi, just as the Tughluq rulers brought Asokan pillars to Delhi in the 1300s.