Repair history of Qutubminar
Qutub Minar was damaged by earthquake in 1505 and It was repaired by Sikandar Lodi. Major. R. Smith repaired and restored the Qutub Minar in 1829.
What you see of the Qutb today is the result of additions made by his successor Iltutmish and later by Firoz Shah Tughlaq. Sikandar Lodi too made repairs to the structure in the sixteenth century. The British attempted to replace a fallen cupola, but this was so inconsistent with the rest of the minaret that it was removed and now forms part of the complex. The wondrous Iron Pillar, the unfinished Alai Minar, and the tomb of Iltutmish are some of the other structures in the complex.