"Let us quote the version given in the Oxford History of Islam: The immense congregational mosque in Delhi known as Quwwat al-Islam (Might of Islam) was one of the first built in India. Begun in 1191, the mosque stands on the site of a pre-Islamic temple whose ruins were incorporated in the structure. The tall iron pillar in the courtyard, originally dedicated to the Indian god Vishnu around 400, was re-erected as a trophy to symbolize Islam's triumph over Hinduism."