In Harry Potter e Relíquias da Morte parte II, Harry percebe que o Diadema Perdido de Rowena Ravenclaw está na escola de bruxaria e bruxaria de Hogwarts e que mais tarde Harry o encontra na sala de requisitos. Alguém pode me indicar como e quando Voldemort escondeu o Diadema (Horcrux) na escola como ele deve ter que visitar a escola para esconder isso?
Ele escondeu lá quando veio pedir a posição de Defesa Contra as Artes das Trevas.
Isso fica claro nos livros:
So Voldemort had managed to wheedle the location of the lost diadem out of the Gray Lady. He had traveled to that far-flung forest and retrieved the diadem from its hiding place, perhaps as soon as he left Hogwarts, before he even started work at Borgin and Burkes.
And wouldn’t those secluded Albanian woods have seemed an excellent refuge when, so much later, Voldemort had needed a place to lie low, undisturbed, for ten long years?
But the diadem, once it became his precious Horcrux, had not been left in that lowly tree.... No, the diadem had been returned secretly to its true home, and Voldemort must have put it there —
“— the night he asked for a job!” said Harry, finishing his thought.
“I beg your pardon?”
“He hid the diadem in the castle, the night he asked Dumbledore to let him teach!” said Harry.
Saying it out loud enabled him to make sense of it all. “He must’ve hidden the diadem on his way up to, or down from, Dumbledore’s office! But it was still worth trying to get the job — then he might’ve got the chance to nick Gryffindor’s sword as well — thank you, thanks!”
Harry Potter and the Deathly Hallows, chapter 31: "The Battle of Hogwarts" (emphasis added)