Nurmengrad is a formidable, jet-black fortress built by the Dark Wizard Gellert Grindelwald to imprison his enemies. The structure is described as tall and forbidding. Carved over its entrance is the slogan “For the Greater Good”, a phrase he and a young Albus Dumbledore once shared as a justification for their plans to establish a new wizarding world order. Following his legendary duel with Dumbledore in 1945, Grindelwald was defeated and subsequently incarcerated within his own creation. He was held in the highest cell of Nurmengrad, where he remained the sole prisoner for over fifty years until his death.
Nurmengrad appears in Harry Potter and the Deathly Hallows when Lord Voldemort is hunting for the Elder Wand. Having learned that Grindelwald once possessed it, Voldemort travels to the prison to interrogate him. Through his mental connection with the Dark Lord, Harry Potter witnesses Voldemort's arrival at the prison and the subsequent confrontation. Inside the cell, Voldemort finds an aged, emaciated Grindelwald. However, Grindelwald shows no fear, taunting Voldemort and refusing to disclose any information about the Elder Wand's location or its last master. Enraged by Grindelwald's defiance, Voldemort murders him. This event is crucial as it ultimately helps Harry deduce that Albus Dumbledore was the true master of the wand after defeating Grindelwald.