Süpplingenburg's a municipality of 700 inhabitants (2003) in the district of Helmstedt, Lower Saxony, Germany. It's part of the collective municipality (Samtgemeinde) of Nord-Elm. The village developed next to a 10th century water castle at the Schunter river, probably erected by the Counts of Haldensleben who then held the office of margraves of the Northern March. Gertrud von Haldensleben's daughter, Hedwig of Formbach, married Count Gebhard of Supplinburg. Until 1173 the castle was the… (More on Supplinburg)