Can I fly to Beijing for one day to see Great Wall and then to Shanghai to catch my return to US?

Hello,
I have a return flight to the U.S. on December 19 from Shanghai - Florida. I'd like to see the Great Wall. From Hanoi Vietname, can I fly to one way Beijing with a 24 hour stop to see the Great Wall, and then with a separate ticket fly one way to Shanghai the next day to catch my return flight on AA to the U.S?
Best,
Suzi