Not to be confused with the city by the same name in China's Yunnan Province in southwest China, this Fuyuan is located in Heilongjiang Province on the Heilong River (for which the province, Heilongjiang, is named; the Russians call it the Amur River). Geographically, it's China's easternmost city.
It's about a 12-to-13-hour train ride to Fuyuan from the Harbin East train station with numerous stops along the way. The Fuyuan train station is several kilometers outside of Fuyuan itself; so taxi or public bus are your only means of getting between the two points.
I've got to tell you that Fuyuan is really small! How small? Well, let's just say that you can walk from one end to the other - whether north to south or east to west. The walk itself, especially east to west, is a bit hilly.
Other than geographical curiosity (being able to say you've been to China's easternmost city), there really isn't much to see in Fuyuan. Pretty much anything that might count as a tourist attraction (at least if you go by the list tripadvisor has - https://www.tripadvisor.com.sg/Attractions-g1372298-Activities-Fuyuan_County_Heilongjiang.html) is between 20 and 40 kilometers south and I wasn't interested because it misses the point of going to China's easternmost city: being as far east as you can go in China.
Within the city itself, if you can really call it a city, there isn't a lot to see. While tripadvisor did list Mangjitazhan Old City, the "old city" was just a bunch of old houses scattered throughout Fuyuan and most of them were practically ruins. Not on tripadvisor's list were a small national forest and a river walk, both of which would be better to do in the summer than in the coldest month of the year.
As an urban explorer, I often just pick a direction and start walking. That's pretty much how I spent my time in Fuyan. A couple of days I headed down toward the river, another to the south end of the city, another to the north end, and another to the west end (where, interestingly enough, there's a sort of gate marking the entrance to this little city). In between were numerous shops and restaurants - no shopping malls or food courts, though. Near the south end of the city was a church that is still in use, surrounded by some of those old houses I mentioned earlier.
Fuyuan is worth visiting if you want to be able to say you've been to China's easternmost city. Tripadvisor lists as one of its things to do a place several kilometers south as a place to watch the sunrise. Don't bother! If you really want to see the sun as it rises in the east, go stand along the river in Fuyan itself. Walk the streets of Fuyuan. Browse the shops. Enjoy typical Dongbei cuisine in any one of a large number of restaurants. Sturgeon are a common catch in the Heilong (Amur) River. In fact, in May 2018, a local fisherman caught a 514 kilogram female sturgeon (https://news.cgtn.com/news/3d3d414f30416a4e77457a6333566d54/share_p.html). Fuyuan is a nice little place to spend a few leisurely days.