Delhi- Alai Minar

Alauddin Khilji started building the Alai Minar, after he had doubled the size of Quwwat ul-Islam mosque. He conceived this tower to be two times higher than Qutb Minar in proportion with the enlarged mosque. The construction was however abandoned, just after the completion of the 24.5-metre-high (80 ft) first-story core; soon after death of Ala-ud-din in 1316, and never taken up by his successors of Khilji dynasty. The first story of the Alai Minar, a giant rubble masonry core, still stands today, which was evidently intended to be covered with dressed stone later on. (Wikipedia)