What Makes for a Good Dungeon Entrance Chamber?

The only thing more important than the dungeon entrance (be it to the mythic underworld or some place more realistic) with regards to setting the right impression in a dungeon is its entrance chamber.   

After all, that first chamber sets the tone for the rest of the dungeon. But that begs the question, what makes up a good entrance chamber?

Among the many gems buried in the AD&D DMG is this image of suggested start areas for a random dungeon from Appendix A.  The one thing each of these start areas have in common is multiple directions for delvers to choose from.

So, the first thing that a good entrance chamber should have is immediate multiple exit options, be they open corridors, closed doors (locked, stuck, or just closed), or even something else, such as shafts or stairways heading deeper into the hole that eats people dungeon.  Honestly, having this much is a solid start, but there is always more to consider.

The second thing that a good entrance chamber should contain is something for the PCs/players to interact with, such as a pool, statue, shrine, crates under the stairs, or something else (to include a trap).  Yes, this amounts to more options for the players, but options that may eat time as its investigated, but may also provide useful treasure or tangible clues regarding what is to come.

Which leads to the third and final thing that a good entrance chamber should contain: evidence of past explorers and/or current inhabitants.  Veteran dungeon delvers know that information is crucial to dungeon mastery, and this opening chamber provides the DM a legitimate place to provide such information to attentive players.  

What said players do with the information is up to them, but at least the DM has done their job in providing it.

This evidence can be in the form of tracks, graffiti (my favorite), trash, discarded gear, (partial) corpses in various states of decay, odors, sounds, or anything else the DM can imagine - or the dice suggest.  Monsters and explorers leave sign or spoor, just like real animals do.  And just like real animals, such spoor can be used to track or evade such monsters.

For example, I had a dungeon where drag marks and footprints led to an otherwise solid wall, signaling a secret door without actually opening it.  Alternatively, consider the situation where the PCs enter into a chamber to find a shed snakeskin at least 20' long and probably 5'-6' in diameter blocking one of the corridors (the snake used the door jamb as a scrape).  Do they harvest the snakeskin, move it and head down that corridor, or go the other way entirely?

(As an aside, do other reptilian critters like dragons molt and shed skins as they grow?  I think those in my world do.)

All of this shows the players that their PCs are assuredly not alone in the dark tunnels.

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In short, use that opening chamber to impress the players and make them want to return next week to explore more of the megadungeon. Besides, this entrance chamber is likely to be many folks' debut to the #Dungeon23 community, so makes for a fine first impression there.