i'm at pudong. what is the nearest location to see the great wall?

There is no great wall section in Shanghai, so I would suggest you go to Beijing for this experience.

You can fly to Beijing first. After landing at the capital airport, you can take airport shuttle line 2 (Xidan Line) to Xizhimenqiaonan, and the walk north to the north railway station. From there you can take the S trains to reach Badaling Great Wall.