Obertshausen () is a town in the Offenbach district in the Regierungsbezirk of Darmstadt in the state of Hesse, Germany. It has around 24,000 inhabitants. Geography Location Obertshausen is one of 13 towns and municipalities in the Offenbach district. The town lies in the thickly wooded eastern part of the Rhine-Main lowland south of the Main and southeast of Frankfurt am Main and Offenbach am Main at an elevation of 112 m above sea level. Southwest of the town is found Darmstadt, the seat of the like-named Regierungsbezirk. To the northeast lies the town of Hanau (Main-Kinzig-Kreis). Obertshausen lies in the southern part of Hesse, not far from the Odenwald and the Spessart. Municipal area's extent The municipal area stretches over 13.7 km², of which 7.8 km² is woodland, open land and cropland Neighbouring communities Obertshausen borders in the northwest on the district-free city of Offenbach am Main with its outlying centres of Bieber and Tempelsee, in the north on the town of Mühlheim (centre of Lämmerspiel), in the northeast on the town of Hanau (Main-Kinzig-Kreis) with its outlying centres of Steinheim and Klein-Auheim, in the east on the community of Hainburg, in the southeast on the town of Rodgau (centre of Weiskirchen) and in the southwest on the town of Heusenstamm. Constituent communities Obertshausen's Stadtteile are Obertshausen and Hausen, each of which has roughly the same population. History In 865, Obertshausen had its first documentary mention under the name Oberdueshuson in a paper from the Benedictine monastery at Seligenstadt as one of the monastery's landholdings. In 1069, Heinrich IV donated to Saint Jacob's Monastery in Mainz some newly cleared land in the Wildbann Dreieich (a royal hunting forest). The land lay near the village of Hyson in the Maingau. At this time, the Lords of Hagenhausen-Eppstein exercised lordly rights (Hoheitsrechte) in Obertshausen and Hausen. In Obertshausen stood a moated castle shaped like a defensive tower, called the Burgk im Hayn (or Burg im Hayn in modern German spelling). The Lords of Hausen, a sideline of those of Hagenhausen, once had holdings here. In the Middle Ages, feudal lords changed very often. The Lords of Eppstein, Ullrich von Hanau and Archbishop Conrad III of Mainz were some of the land's owners. In 1425, Hausen and Obertshausen, as part of the Amt of Steinheim, w sold by the Lords of Eppstein to Electoral Mainz. The Thirty Years' War and the Plague