When Sultan Alauddin Khilji was ruling Delhi and parts of India, he had the ambition to be Sikander e Sani or second Alexander. His wazir very appropriately advised that he should first consolidate his empire and put his house in order. Alauddin Khilji then set about framing his famous administrative reforms for he knew steady prices, inflation under control and taxes were the backbone of any country that had to support a large army.
( photo by Rohan Venkat)
His market reforms are famous. He regulated supply of grains, cattle, slaves, cloth eyc to the markets and their prices. Large whole scale mandis ( markets) were established in the area of Mehrauli. . A controller of market (shahna-i-mandi) intelligence officers (barids) and secret spies (munhiyan) were appointed. The grain merchants were placed under the Shahna-i-mandi. Regrating (influencing the market unfairly) was prohibited.
One such mandi must have been in the Lado Sarai Area. Every area had its own Mosque and so did this.
It is none other than the one known as Madhi Masjid today. Somewhere along the line the word got corrupted
I had always wondered because the word made no sense to me unless it came from madah or praise.
Maulvi Ashraf Hussain in his book on Delhi’s epigraphy written in 1936 calls it Mandiwali Masjid and that of course makes perfect sense.
( photo by Syed Mohammed Qasim for Where Stones Speak)
One enters it through a beautiful gateway built in the Lodi and early Mughal style of architecture. Not much is known of who built it and when. The gateway has lovely Rajasthan Jharokha and has steps leading upto it. 
The spandrel on the central arch has plaster medallions with Bismillah ar Rahman at Rahim followed by the Islamic Creed or Kalima.
From the entrance arcade itself the Qibla wall of the masjid can be seen beyond the huge courtyard. There are a few random graves there.
( photo by Rameen Khan)
One can immediately see that there are covered prayer chambers on either side of the open Qibla wall which was obviously the main prayer area.
These rooms were possibly used by the students and teachers of the madrasa that seems to have flourished here as the mehrabs have open windows.
These were also decorated with lime plaster medallions but those are lost nowm
The ayatal kursi on the side chamber incised in plaster
The outer walls have small turrets on either side.
The cells to house the students and for the madrasa as was common in those days.
The entire Mosque is very attractive and a pity it’s forgotten as its out of the boundaries of Mehrauli Archaeological Park. It’s on the lane leading to the Dada Bari temple near Ashoka Mission.