Letters in italics refer to marked spots on the map. Sector numbers in boldface are secrets which count toward the end-of-level tally.
Essentials
Other points of interest
Secrets
After raising the tower stairs, go up to the top and press on the wall to open it. It contains Armor and some cells. Inside the compartment, you can go through the wall to the left for a Megasphere. (sector 241)
After taking the teleporter that you had to lower by pressing a button where an Arch-vile was, immediately turn around and open the wall. There is an Energy cell pack there. (sector 230)
After defeating the Cyberdemon and using the Blue skull key near the teleporter destination mentioned in Secret #2, a new button will be made available in the octagonal corridor after pressing the button. A wall will open to the right of the Blue Skull Button containing a Berserk pack. (sector 235)
Secret #3 opens the wall behind the Blue Skull Button containing a Spectre and a Stimpak; this room counts as the secret. The button in this room lowers the Soul sphere present at the end of the level. (sector 207)
Bugs
After raising the tower stairs, it is possible to fall through one of the stairs. Doing so will result in the player getting stuck in a small area where three of the four walls surrounding the player have the HOM effect bug. (sector 221)