Read this: It took about 20 years to build the city from 1911. Many elements of New Delhi architecture borrow from indigenous sources; however, they fit into a British Classical/Palladian tradition. The fact that there were any indigenous features in the design were due to the persistence and urging of both the Viceroy Lord Hardinge and historians like E.B. Havell.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): Approximately how long did it take to build New Delhi?
20 years