Feb. 15, 2011 -- The underground dungeon where Josef Fritzl kept his daughter an imprisoned sex slave for decades will be permanently sealed by Austrian officials, after teenagers began using the lair for illicit parties.

Broken booze bottles and drug paraphernalia left by the partying teens are scattered among the soiled mattresses and old computers Fritzl, the convicted murderer and rapist, left behind in the maze of rooms underneath his home in the Austrian town of Amstetten, outside Vienna.

The unlit rooms stink and are covered in rat feces, one of the teens who entered the dungeon told Britain's Daily Mail.

For 24 years the subterranean dungeon housed Fritzl's daughter Elisabeth and the six children she had by him. Elisabeth gave birth to a seventh child who did not survive. Fritzl was charged with the baby's death after authorities discovered the cellar in 2008.

All the while, Elisabeth's mother, Rosemarie, lived upstairs in the home she shared with Fritzl, unaware that her daughter was imprisoned in the basement.

After Fritzl's arrest, trespassing partygoers accessed the basement through an unlocked garage door, according to the Daily Mail.

Each of the basement's eight rooms was separated by a locked door. The final room, in which Elisabeth was mainly confined, was accessible only through a three-foot sold steel door hidden by rows of shelves.

"The shelving has all been stripped away and the secret cellar door was ajar. There is no lock on it. But I didn't go into there, although it was clear people had," one witness told the paper.

"The smell is atrocious," he said. "There has been no air, and mildew covers the walls while the floors have deep puddles in places. It has become somewhat 'cool' among the young in Amstetten to say you have been down in 'the cellar.' You don't have to say which one -- everyone knows what you mean."

'The walls are very thick'

The partygoer said the floors are covered in rat droppings and cigarette butts. There is no power in the house, which authorities plan to tear down in the spring, so intruders burn candles.

"The walls are very thick. You can play music down there and no one will hear, or see any light," he said.

"The word went out before Christmas that the garage door was open. You descend down a slope into his garage and then into the cellar. It's easy. The cops stopped watching the place long ago."

Fritzl, 75, pleaded guilty to charges of rape, enslavement and negligent homicide. He is currently serving a life sentence. Elisabeth Fritzl, freed from the labyrinth in 2008, lives quietly with her children in a well-guarded home in a village 40 miles from Amstetten.

Calls made by ABCNews.com to the Amstetten police were not returned.