Blankenberg is a district of the municipality of Rosenthal am Rennsteig in the Saale-Orla district of Thuringia. Blankenberg was first mentioned in a document in 1232. It was located on the northern border of the Regnitzland and belonged to the lordship of the bailiffs of Weida, Gera and Plauen. As early as 1258, Blankenberg was referred to as a fortress on the Saale, which must have meant the castle known as Schloss Blankenberg. Blankenberg Castle existed until the end of the Second World War and was demolished without necessity on June 14, 1948. The ruins can still be visited today.
The Lords of Blankenberg were also named as the lords of the manors of Blankenstein, Harra and Kießling in 1392. The castle changed hands several times over the years. The Blankenberg manor was the patron saint of the former pilgrimage church in Arlas. In addition to the manor, the village had a hammer mill called Katzenhammer, a sawmill and a field brickworks.
Blankenberg's coat of arms shows the castle against a blue background, on a green wooded hill, with a river below and finally three paper bows in the lower area. This emphasizes the elevated position of the original castle and thus of the town on a wooded hill above the Saale. The sheets of paper are a reference to the former paper production in the village. The paper mill in Blankenberg continued to produce paper until 1994. Paper production began in the village as early as 1842, which increased over the years and was bought up by the factory in Blankenstein in 1894.
Unlike places like Harra or Blankenstein, Blankenberg belonged to Prussia and was therefore a Prussian exclave. This is because Blankenberg fell to Prussia on February 10, 1805 as part of the negotiations at the Congress of Vienna following the victory against Napoleon. It had previously belonged to the Duchy of Saxony.