This level occupies the map slot MAP58. For other maps which occupy this slot, see Category:MAP58.
MAP58: The Mansion is a secret map that appears in the PlayStation and Saturn versions of Doom II which can be accessed from MAP44: Suburbs. It is built as a huge, house-like structure befitting the level's name, containing multiple hidden and closed off areas and plentiful enemies.
The player can access the other hidden stage, Club Doom from here.
As you pass through the blue key door, as you turn on the first left there's a hidden door, open it to reveal 4 stimpacks
Of all of the corners of the rising teleporters. one of them adjacent to the one at the bottom lowers to reveal a switch, quickly hit this, then backstep into the teleporter, fall off the ledge leading into the exit room, turn right and run into the dark room where you'll enter a secret room with a teleporter to take you into the room where the blue key pillar is and a switch, this is the exit to the secret level Club Doom.
There is more than one lowering pillar, another two of them contains a plasma gun and a berserk, use the automap to reveal them, they should have a yellow line on them.
Down the corridor leading to the ledge where the exit is, there is a green torch, activate it and a elevator lowers to reveal a rocket lined passage. At the end there is two alcoves containing a chainsaw and mega armor. You may need to continuously go into the chainsaw alcove and then flick the switch to reveal another passage leading up to the corridor to the right of the ledge
On the ledge where the door leading into the Hell Knight Cage Room go the furthest end of the bookshelves and open it, a switch is flicked and a passage is revealed to a teleporter, it takes you to the rising teleporter room.