Hi, there are many must sees in Shanghai, such as the Bund, Oriental Pearl TV Tower, Yuyuan Garden and Shanghai Old Street, you can refer to Shanghai Tours(https://www.travelchinaguide.com/package/shanghai.htm) since there are destinations as well as itineraries suggested. For one day time, I suggest you make a side tour to Hangzhou, the Shanghai-Hangzhou High Speed Rail make it only one hour to travel between Hangzhou and Shanghai, you can take the train to Hangzhou in the morning and back to Shanghai in the evening.