Old ruins of a Roman castle show the importance of Marktbreit's location during the era of Emperor Augustus. It was first mentioned as "broite inferior" in a document of the count of Castell in 1266. It is very likely that there was a settlement for some hundred years at the delta of the Breitbach. In 1557, King Ferdinand allowed the settlement to hold markets, and the name Marktbreit was given to the small town. In the 17th and 18th century Marktbreit was an important marketplace because the shortest way to the Danube from the Main (which ends in the Rhine) starts in Marktbreit.