Facing page: Fig. 56: THE DIVING WELL AT THE QUTB, photograph by Robert and Harriet Tytler, 1858. The Gandhak ki Baoli or step-well in Mehrauli was built by Iltutmish (1211-36). It is supposedly named after the strong presence of sulphur (gandhak) in the water which was said to have tremendous healing properties. It is six storeys deep into the centre of the earth and was used to provide fresh water to the area. British Library, London, Photo 53/(13).