Bad Blankenburg is a spa town in the district of Saalfeld-Rudolstadt, in Thuringia, Germany. It is situated 6 km southwest of Rudolstadt, and 37 km southeast of Erfurt. It is most famous for being the location of the first kindergarten of Friedrich Wilhelm August Fröbel, in 1837. In the nineteenth century, Bad Blankenburg was part of the small principality of Schwarzburg-Rudolstadt. Bad Blankenburg is the headquarter of Deutsche Evangelische Allianz, the net of copperation of most Protestant churches in Germany.