Pir Ghaib is the name given to an unusual and mysterious Tughlaq-era building on the northern ridge, north of Hindu Rao hospital. I had covered that building in my post on Firoz Shah Tughlaq’s Delhi. On my earlier visit to Pir Ghaib I had missed the nearby baoli that is associated with the Tughlaq building. The baoli is from the same period (14th c.) and has an equally mysterious quality to it. The Pir Ghaib photo are also in a flickr set.