The truth is there are not that many things to see in Tonglu. It is just another provincial city in China, still there are nice places around Tonglu. But since you are in the city, one of most "impressing" things to see will prbably be the People's Square. That is waht amazes me in China - every city, even small one will have a huge People's Square with nice architecture and big ground.
I checked on Google Earth snapshots of Tonglu and out of all gray buildings you can easily notice the People's Square. I'll see, maybe I can this satelite image snapshot later.