From Stamps of the World
Altenau is a town and a former municipality in the district of Goslar, in Lower Saxony, Germany. Since 1 January 2015 it is part of the town Clausthal-Zellerfeld.
It is situated in the middle of the Harz mountains, between Clausthal-Zellerfeld and the Brocken. It was part of the former Samtgemeinde ("collective municipality") Oberharz.
Altneau was in the British Zone of occupation, Post WWII and belonged to the Braunchschweig postal district using PLZ 20b.
Poor Ortswerbestempel reads ALTENAU (OBERHARZ) Luftkurort und Wintersportplatz 500-600m.