Valley of the Dead
Valley of the Dead is located immediately below the castle. You either must drop here via a trap door from the castle, or teleport with controlled level teleport. The level layout is always the same. Somewhere near the lower right is stairs up which will lead back to the castle.
This level contains several graveyards, and a temple of moloch, with attending priest. The entrance to gehennom is behind a secret door, accessible via the temple.