Lilith's Chamber is an area in Hell that had been sealed up for ages according to the demon Belphegor. This room is located down a corridor which is adorned by six statues of cloaked skeletal figures in demonic prayer. In her chamber, Lilith kept many powerful objects, among them a piece of jewelry known as the Haxon Ring as well as the Crook -- which is actually a ram's horn -- that once blown can call all demons on Earth to Hell.
When God decided to initiate the end and opened a rupture to Hell, it causes every door in Hell to open, including Lilith's Chamber. The demons and damned souls who did not take the opportunity to escape at first chance raided the chamber before the arrival of Castiel and Belphegor, including Malfayan. Castiel was able to open the box containing the Crook, only to be attacked by Ardat who reveals Belphegor really intends to use the Crook to gain power for himself. Castiel is forced to smite Belphegor, burning Jack's corpse to a charred skeleton and destroying the Crook. Jack's corpse was apparently left in Lilith's Chamber when Castiel escaped from Hell.
When the Winchesters and Castiel return to Hell in search of Michael, they arrive near Lilith's Chamber and have a brawl with several demons outside. It is here that they learn that Rowena is the new Queen of Hell.