Reproduced from Wikipedia.
This mosque is located in the Main Bazaar (now called Chowk Bazaar) of the city. It was named so because it was located in the midst of the flower sellers' bazaar. The story recorded in a book titled "Early History of Multan" says that the Mughal Emperor Farrukh Sher (1713-1718 AD) on his visit to Multan, being childless, asked a fakir to pray on his behalf, that he might be blessed with a male issue. The fakir prayed for him, and a son was born to the Empress. His Majesty, through the governor of Multan, presented the fakir with an offering of Rs. 80,000, and with this money the liberal minded fakir had this mosque built.
This is now located in Chowk Bazar of inner old Multan city. Masjid needs improvement and promotion.