The Depths of Hell…
“Azkaban was originally home to a sorcerer who called himself Ekrizdis.
Ekrizdis, who is believed to have been insane, was a practitioner of the worst kinds of Dark Arts.
Alone in the middle of the ocean, he lured, tortured and killed Muggle sailors, apparently for pleasure, and only when he died, and the concealment charms he had cast faded away, did the Ministry of Magic realize that either island or building existed.
Those who entered to investigate refused afterwards to talk of what they had found inside, but the least frightening part of it was that the place was infested with Dementors.
Sadistic by nature, Rowle, an authoritarian who had risen to power on an anti-Muggle agenda, insisted on using Azkaban as a prison. He claimed that the Dementors living there were an advantage: they could be harnessed as guards, saving the Ministry time, trouble and expense.
In spite of opposition from many wizards, Rowle carried out his plan and soon a steady trickle of prisoners had been placed there. None ever emerged.
By the time that Eldritch Diggory took over as Minister for Magic, the prison had been operating for fifteen years. There had been no breakouts and no breaches of security. The new prison seemed to be working well.
It was only when Diggory went to visit that he realised exactly what conditions inside were like. Prisoners were mostly insane and a graveyard had been established to accommodate those that died of despair.
Diggory had been so horrified by what he had seen inside Azkaban that he pressed the committee to find alternatives. Experts explained to him that the only reason the Dementors were (mostly) confined to the island was that they were being provided with a constant supply of souls on which to feed. If deprived of prisoners, they were likely to abandon the prison and head for the mainland.
From that time until the advent of Kingsley Shacklebolt, no Minister ever seriously considered closing Azkaban. They turned a blind eye to the inhumane conditions inside the fortress.
Nearly three centuries passed before that record was broken. A young man was successfully smuggled out of the prison when his visiting mother exchanged places with him, something that the blind and loveless Dementors could not detect and would have never expected.
This escape was followed by another, still more ingenious and impressive, when Sirius Black managed to evade the Dementors… single-handed.