The Qutub Minar is a 73-meter tall minaret that forms a part of the Qutab complex in New Delhi. Construction was started at around 1192, and continued by several rulers until fully completed.
The Iron pillar of Delhi is a 7 meter iron column, believed to be erected originally in 3rd to 4th century CE by King Chandra, and currently standing in the Qutub complex in New Delhi. Column is famous for the rust-resistant kind of low-carbon iron used in its construction.