Dungeon

...it's in the name!
The World's Most Popular Role-Playing Game introduced many of us to the underground adventure. The "dungeon" is often situated beneath a castle. Such was the case with Blackmoor and Greyhawk, the original campaign settings of creators Dave Arneson and Gary Gygax respectively. In the original edition of the game there are instructions on how to draw up a dungeon map, populate it with monsters, traps and treasure and it offers suggestions for how to run your players through the dungeon adventure you create. The three Little Brown Books talk about player perspective including mapping, marching order, movement along the corridors and tunnels, opening stuck doors, torches and other sources of light, and various other aspects of underground dungeon delving.

The dungeon, with its floors, ceiling and walls, is a self contained environment. It allows the referee some degree of setting control and the ability to predict where the characters will go. Players are imaginative and creative problem solvers and they will invariably come up with some plan of action during play that forces improvisation onto the best prepared referee, but dungeon walls make the task somewhat more manageable.
The dungeon offers many advantages to the referee in terms of it being a unique environment and one that instantly suggests to the characters that they have entered someplace quite different from the mundane. The underground is seen as someplace magical where the laws we experience on the surface don't necessarily apply - physical laws nor man-made ones. Creatures that dwell beneath may see perfectly well in darkness, doors which readily open for the underworld denizens will often stick closed and must be forced by characters, making a great amount of noise... and perhaps attracting some monster wandering the halls.
The dungeon prepares new players and perhaps more importantly, new referees, for the task of creating great gaming experiences while learning the game under somewhat controlled conditions. The dungeon offers nearly everything available in the game and does so on a manageable level, with walls. It sets limits and keeps the action confined to a manageable space while the novice learns and develops confidence.
Refereeing the dungeon environment is a skill and designing and running a good dungeon will offer your players a flavorful and challenging playground in which to become heroes. This is something to take pride in as a referee. Published dungeons abound, and the better examples have garnered a reputation among players. As much fun as sharing our war-stories about those oft-played published dungeon adventures can be, the real challenge for the referee is to devise their own personal "masterpiece" dungeon - one that can define a campaign.
The dungeon may start out as a map, or even better as a concept or theme, which the referee hopes to bring life to through its expression in the form of the dungeon. Populating the dungeon is a task that can benefit from the application of logic. The best dungeons seem to make sense in terms of how and why the denizens are making it their home. Opportunities for exploration, role-play and of course combat are essential elements of the dungeon, and each of these should challenge the actual players, not just their character sheets.

There is a lot more to a great dungeon experience than kicking in door after door, slaughtering creatures and hauling out loads of treasure, fun as that style of play can be. Great dungeons facilitate great stories. Through their play, the players/characters shape the dungeon, and perhaps the greater world above and below. Mysteries are solved, secrets revealed, and the balance of power can shift as the characters go about their business inside the dungeon.
The referee's adventure may have started with designing a dungeon, but it usually isn't long before other fantastic non-dungeon locations are added to the mix. Places of mystery and imagination set the stage for play perhaps as well as dungeons and certainly add variety to the campaign. Who hasn't thought of a wizard's tower as a place for adventure! They all share many of the same essential elements learned while in the dungeon and they are all locations where magical adventure awaits and referee planning pays off. The wizard's tower, the evil temple, and the ruins of a lost city, these are all iconic locations of fantastic adventure and have more in common than not with the dungeon!