Bad Belzig (), until 2010 Belzig, is a historic town in Brandenburg, Germany located about southwest of Berlin. It is the capital of the Potsdam-Mittelmark district. Geography Bad Belzig is located within the Fläming hill range and in the centre of the High Fläming Nature Park. The plains north of the town are home to one of the few great bustard populations in Germany. Since 2003, when 14 surrounding villages were incorporated into Bad Belzig, some of them voluntarily, others by Brandenburg Landtag (state parliament) legislation, Bad Belzig has an area of 234.83 km². These villages became districts (Ortsteile) of Belzig: The forest of Verlorenwasser near Werbig encompassed the geographical centre of East Germany. History A Slavic fort of Belizi was first mentioned in a 997 deed issued by Emperor Otto III in favour of the Archbishopric of Magdeburg. Whether this denotation refers to Bad Belzig or the neighbouring town of Beelitz has not been conclusively established. Nevertheless, both towns celebrated their 1000 years anniversary in 1997. The estates however had actually already been lost in the Slavic uprising of 983 and were not conquered again until 1153 by Albert the Bear from the House of Ascania. In 1251 the castle (Burg Eisenhardt) and the adjacent settlement became part of Saxe-Wittenberg under Albert's successor Duke Albert I. However it was claimed by the archbishops of Magdeburg, whose forces devastated Belzig in 1406. The rebuilt castle was again seized by the Hussite general Prokop the Great when he invaded Saxony in 1429, after which Elector Ernest of Saxony from the House of Wettin enlarged it to a fortress. During the Thirty Years' War it was seized by the troops of the Swedish Empire in 1636, after Elector John George I had allied with Emperor Ferdinand II in the Peace of Prague. The Romanesque St Mary's Church was built in the late 13th century. According to an inscription in the keystone of the western entrance, Martin Luther preached here on January 14, 1530. Eisenhardt Castle. Bad Belzig was granted town privileges in 1702. During the War of the Sixth Coalition on August 27, 1813 troops of the French Empire and Saxony were attacked by Prussian and Russian forces near the village of Hagelberg. The encounter ended in a French defeat, while several Saxon units went over to the Prussians. According to the Final Act of the 1815 Congress of Vienna Bad Belzig