The House of Guttenberg is a prominent Franconian family which traces its origins back to 1149 with a Gundeloh v. Blassenberg (Plassenberg). Though, the first mention in a document is dated 1158. The name Guttenberg is derived from Guttenberg and was adopted by a Heinrich von Blassenberg around 1310. The Plassenberg family were ministerial of the Counts of Andechs (later the dukes of Andechs-Meranien) and used as their seat the Plassenburg of Kulmbach. The castle of Guttenberg remains the main seat of the family. The family currently consists of two branches. The elder branch, von und zu Guttenberg and the younger Steinhausen branch. In 1700 the family rose from Reichsritter (Imperial Knights) to Reichsfreiherr (Barons of the Holy Roman Empire). After the Holy Roman Empire dissolved, they were made Freiherr (barons) of Bavaria (1814 & 1817). According to historian Werner Wagenhöfer, the Guttenberg family is the most researched family of the low nobility in Franconia along with the Seckendorff and Bibra families.