Character: The smell of death surrounds me!
The Catacombs are the second set of levels in Diablo I, consisting of levels 5-8.
This interior is filled dark corridors, with much less open space, a somewhat maze like layout and a much more gloomy atmosphere, as with the Cathedral, with cylinder-shaped towers with stairs which makes your way to the next level.
Just like how every first level of a level set has a staircase up to town, so do the Catacombs; the entrance is a hole looks like a crypt-shaped building near the cows. Mousing over it says "DOWN TO CATACOMBS."
Catacombs contains half of the multiplayer quests, as well as five singleplayer-only quests. Three of the four (but never all) of the singleplayer quests will appear in each game, except for the Chamber of Bone.
The Chamber of Bone, for the singleplayer-only the chamber of the same name quest, is found most often on Level 6.