Drachensberg was a castle in Germany, situated hundreds of miles from Berlin. It was the private property of Reichsführer Heinrich Himmler, the Nazi leader of the Schutzstaffel and the Gestapo, during the 1930s.
Owing to his obsession with Teutonic mythology and the occult, Himmler granted Doctor Felix Kriegslieter and the Black Coven use of the Castle Tower as a base to practise their black magic rituals. In reality, the coven was a War Lord front, using their technology to become the puppet masters of a Nazi conquest of the Earth. They set up a transmat link between the castle and Kronprinzenstrasse in Berlin and constructed a nuclear reactor in the basement. Himmler largely left the Castle Tower alone apart from the occasional visit. The Coven performed a sacrifices to keep him onside.
Black Coven ritual in Drachensberg. (PROSE: Timewyrm: Exodus)
In September 1939, during the earliest stages of World War II, the Seventh Doctor and Ace were imprisoned in Drachensberg while investigating the War Lords. They escaped, coinciding with an attack on the castle by Hermann Goering at the head of an armoured column, whom the Doctor had alerted about treasonous activities taking place at Drachensberg before heading there himself.
Goering's men engaged with the Coven's brainwashed SS troops around the castle ground before the Doctor and Ace destroyed the castle gates with an anti-aircraft gun, allowing Goering to advance into the courtyard and from there his men wiped out the Coven. Once the Nazi leaders departed, the Doctor overloaded the nuclear reactor. It exploded, destroying the castle, Kriegsleiter and his zombie SS troops, and the advanced technology contained in it.
Drachensberg remained a desolate ruin. A cloud hung above the castle grounds for days after the explosion. People living around the area left or died of radiation poisoning. The area was abandoned and reputed to be cursed. (PROSE: Timewyrm: Exodus)
Himmler owned another castle at Wewelsburg, in Westphalia, which he also used for occult purposes. (PROSE: The Shadow in the Glass)