RRB NTPC 29 April 2016 Paper

(2) The construction of Qutub Minarwas started by Qutub-ud-Din Aibak in 1193, but he only constructed the basement. The construction of the tower was later taken over by his successor Iltutmish, who constructed three more storeys.The last two storeys were completed by Firoz Shah Tughlaq.