The Hall of Hell was a temple filled with the statues of the 48 Demons. It was originally protected by the monk, Souryo until Kagemitsu Daigo killed him and made a pact with the Demons by offering his soul and his son's body parts. The side-effect of not having body parts but grant them demonic powers.
After Hyakkimaru killed all the demons and regained his body parts, the Land Of Daigo has burnt down and the Hall has became cold and old as the destroyed statues is covered in spider's webs and the secondary side effect of the demons' destruction the caster of the pact will be passed away from succumbed of their blood loss. According to The Twelfth Demon and Kagemitsu Daigo, The pact can only work once if the demons statues are intact. But won't work when all of them are destroyed after their deaths.