Information already available, together with certain more recent observations associated with the longevity of the Delhi Pillar are assembled in this paper. These are discussed, and while there is little factual evidence to account for the unusual behavior of the pillar, it has been possible to reject certain previous views and to assemble sufficient direct and indirect evidence to justify a reasonable explanation for the small amount of corrosion that has occurred during the 1600 years’ live of the pillar. Only those metallurgical features that have a bearing on corrosion are considered.