The Manzhouli National Gate Scenic Area is the city's most explicit border landmark, marking the rail and road crossing between China and Russia. The attraction is partly symbolic - gates, border markers, viewing areas, and patriotic displays - but that symbolism is central to Manzhouli's identity as a frontier trading city.
It is worth visiting for the sense of geography as much as for the built structures. From here, Manzhouli's mix of Chinese, Russian, and Inner Mongolian influences makes more sense, especially if you also explore the city's Russian-style streets and border-trade districts.