I’ve been running a 5e campaign since shortly after the full rules set was available, and I admit I’ve not read the whole DMG cover to cover yet. But when I do open it up and go look something up, I often come across one of the sample maps in the volume which in turn has appeared in every odd-numbered edition of the game.
The monastery basement map has been with us since the 1e DMG, made a new appearance in the 3e DMG (and was further expanded in an issue of Dungeon Magazine to finally have a full key instead of just a few rooms detailed), and is back again in a similar-yet-different style in the 5e DMG.
Besides style issues, there is only one major difference between the three versions – in Todd Gamble’s version (in 3e), room 5 is connected to the same hallway that leads to room 4. It isn’t immediately clear in the original map, but the 5e version seems to be accurate that there was intended to be a wall between room 5 and the hallway, making room 5 a secret room only accessible through the crawlway secret doors from room 4.
Two of my favourite parts of the whole map are the descriptions of the secret door in 3 and the secret door in room 28.
Room 3 has a secret door that is significantly above floor level, and a series of notches in the wall just beneath it. The notches used to hold up the wooden raised platform in the south side of the room (the wooden beams would be pushed into the notches to hold the structure up) and the secret door was meant to access this raised platform. It’s this kind of background that makes me think harder when drawing and detailing my own maps.
Room 28 has a secret door that leads in two distinctly different directions – depending on how you open it. Just finding the secret door and triggering it to open will lead to room 29, but knowing the extra-secret triggering mechanism will open it up instead to the stairs at area 30 – the real treasure room of the monastery dungeon.