Montereau-Fault-Yonne, or simply Montereau, is a commune in the Seine-et-Marne department in the Île-de-France region in north-central Fran…Montereau-Fault-Yonne, or simply Montereau, is a commune in the Seine-et-Marne department in the Île-de-France region in north-central France. Montereau-Fault-Yonne straddles the confluence of the rivers Yonne and Seine at the far south-east of the Île-de-France region, 70 km southeast of its administrative centre, Paris. The A5 autoroute passes northeast of the town. Montereau station links by rail Laroche-Migennes, Melun and Paris. It is approximately equidistant between slightly larger Melun and Sens.