This is a downward-extending branch consisting of between 20 and 24 levels; it is reached by the trapdoors found in the Castle, the lowest level of the Dungeons of Doom (alternatively, the first level, the Valley of the Dead, is accessible by level teleport from the Dungeons).

The following dungeon branch connects to Gehennom:

Vlad's Tower (9th to 13th level, DL 34 to DL 42)

The following special levels are found in this branch:

Valley of the Dead (1st level, DL 26 to DL 30)
Asmodeus' Lair (2nd to 7th level, DL 27 to DL 36)
Juiblex' Swamp (4th to 7th level, DL 29 to DL 36)
Baalzebub's Lair (6th to 9th level, DL 31 to DL 38)
Orcus-town (10th to 15th level, DL 35 to DL 44)
Wizard's Tower (11th to 18th levels, DL 36 to DL 47; three consecutive levels)
Fake Wizard's Towers (3rd to 6th levels from bottom, DL 40 to DL 51; two levels)
Vibrating Square (2nd level from bottom, DL 44 to DL 52)
Moloch's Sanctum (Bottom level, DL 45 to DL 53)

(Note that some level ranges are interdependent, so certain combinations of branch/level locations are impossible; for more specific information, see individual entries.)

All non-special levels are mazes. All non-special, non-branching levels are eligible to leave bones. Prayer to one's god is impossible throughout the branch; prayers will instead attract the attention of Moloch.

NetHack 3.4 Spoilers
Dylan O'Donnell (