While many statues of Mao were removed under Deng Xiaoping, the Mao statues at universities survived for the most part. ECNU's was the center of campus and a frequent meeting place for students. I particularly liked doing my banking there for irony. Mao also made for great photos. While a bunch of people doing tai chi in a park like setting could be from China, they could also be in New York, or LA, or Singapore, or any other area with a large Chinese population. A bunch of people doing tai chi in front of a giant statue of Mao can only be in Mainland China.