How long did it take to build the Great Wall of China?
The total time span was many centuries. There are many parts to the Great Wall and different emperors had different parts built. The first parts were completed about 200 BC and the last parts were added over 200 years during the Ming Dynasty (1368-1644).
The most recent rebuilding appears to have been about 500 years ago, except for those parts rebuilt very recently to aid tourism.