Babel

Doom
The Tower of Babel is the boss level (E2M8: Tower of Babel (Doom)) in the second episode of the original Doom. While there is no direct lore explaining its name. It is notable that it 'magically builds' itself on Deimos as the player beats each level. It is from the tower, that the the Marine fights a Cyberdemon and then goes to Hell (for the third Episode).

Doom 2016
This level appears again in the 2016 Doom as unlockable Classic Map called "Doom - Tower of Babel." The enemies are replaced with their updated equivalents, and combat uses the game mechanics of the Doom reboot. A unique variant of the 2016 Cyberdemon is used rather than the boss version encountered in the campaign. There is no lore tied to the level, it is simply unlocked by finding the Classic Map Lever in Lazarus Labs to unlock the mini-area, opening up a small section of the classic map bleeding into the scenery.

A reference to the Doom level's map number is found in the Codex entry for the Spider Mastermind, where "PL E2M8" is UAC's reference number for "a destroyed tower of unknown construction."

Doom Eternal
Tyrants are described as "Demon Lords of the black soul pits of Babel" in their Codex entry though no further context is given. A Tyrant is found guarding the large Abbadon Pit in Nekravol, as well as in the accursed Citadel, the largest Soul Spire itself. The Citadel is but one of several Soul Spires built into the central columns of Nekravol. Most are linked to Argent D'Nur through a Hell Priest created Continuum Gate. There is no Continuum Gate at the Citadel itself, apparently due to the distrust of the Khan Maykr to those under her charge. Soul Spires were designed by the Maykrs to accelerate the processing of mortal victims into Argent Energy.

Art of Doom Eternal
Babel is mentioned in the The Art of Doom Eternal as a former location in Hell: it is unclear what the nature of this location was, though it may be intended to reference the original Doom's Tower of Babel level (E2M8).

The book describes an Archdemon, Erebus, who rules over the Spire City of Dis, risen from the ruins of Babel.

An illustration of the main tower of the Maykr-built facility in Nekravol as "Tower of Babel," (other illustrations refer to the interior of the tower as "Hell Tower - Interior/Exterior" and "Soul Extraction," as the "Tower Entrance," and it describes a structure just outside the tower as Soul Pit). A prize draw for Slayer's Club members in April 2020 also referred to a prize of a piece of Nekravol concept art as "Tower of Babel Lithograph." In-game, the only names given to this tower is the "Citadel.", and "Soul Spire" (with the only possible exception being the reference to Babel mentioned in Tyrant codex.)

As this information is only present outside the game, it is unclear to what extent it is part of the series lore.

Trivia

 * The main tower of Nekravol is visually based on a number of classic illustrations of the Biblical Tower of Babel, particularly Pieter Bruegel's The Tower of Babel series and Athanasius Kircher's Turris Babel.
 * The Steam trading card which uses the concept artwork for the Nekravol tower is called "Tower Babel".