Marktbreit am Main is a town in the district of Kitzingen in the Regierungsbezirk Unterfranken in Bavaria, Germany. It is situated at the most southern point of the Main river. Marktbreit is the birthplace of Alois Alzheimer who first identified the symptoms of what is now known as Alzheimer's disease. With its suburb Gnodstadt, Marktbreit has around 3,700 inhabitants.

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.