is located near Qutab Minar
and is credited to Iltutmish
It is five-storey deep and has a circular wall at its southern end. The name is derived from the smell of sulphur (gandhak) in its water. Tremendous medicinal properties were attributed to the water because of the presence of sulphur in it.
Until some years ago, it was popularly known as the diving well, in which visitors would throw coins and divers would jump in from the upper storey to retrieve the coins. Today, the baoli has very little water and it is not potable.