What is the best month to visit Beijing and climb the Great Wall. I am 64 years old.

Generally speaking, from April-June and September-October is a good period to tour around the Great Wall and the city. The weather conditions are good at that time, neither too hot nor too cold. Notably, it's suggested to avoid going there in early October (Oct 1-7). It will be the Golden Week travel season. Crowded people will bring a lot of inconvenience for elder people.