Rüsselsheim am Main is the largest city in the Groß-Gerau district in the Rhein-Main region of Germany. It is one of seven special status cities in Hessen and is located on the Main, between Frankfurt and Mainz, only a few kilometres from its mouth in Mainz. The suburbs of Bauschheim and Königstädten are included in Rüsselsheim. Rüsselsheim has attained international recognition through the presence of the German car company Opel.

The Main is the longest tributary of the Rhine. It rises as the White Main in the Fichtel Mountains of northeastern Bavaria and flows west through central Germany for 525 kilometres (326 mi) to meet the Rhine below Rüsselsheim, Hesse. The cities of Mainz and Wiesbaden are close to the confluence.