The first level of the dungeon appears to be an old ruin, but it's actually the youngest portion of the entire complex. Most of it was built by Duke Chordille for storage, keeping prisoners, and eventually to honor the goddess Glarias. As the subterranean portion of the keep expanded, the duke's workers found old chambers originally built by Queen Ryssa's dwarves. This allowed the duke's dungeon to connect to the other levels, although the duke kept the rest of the dungeon a secret from all but his most trusted confidants and forbade anyone to explore its depths for fear of rousing something dangerous (a wise move, really--the duke apparently knew something about the nature of dungeons).
After the duke's death and the razing of his keep, others utilized the underground level from time to time, often modifying its chambers to suit their needs. It was a large bandit lair for a few years, for example. The wizard Serrestique used a large portion of it for her own purposes during another period about a decade ago, until she mysteriously disappeared.
Eventually, during a priest's drug-induced vision, the Bestial Host learned of the existence of the temple of the Beast God here and moved in.
Unless the text states otherwise, the level's floors, walls, and ceilings are made of masonry stone. Ceilings are 15 feet high. All doors, unless otherwise described, are simple wooden doors, unlocked, 1 inch thick, with a hardness of 5, 10 hp. 
There are 38 rooms in Level 1. Click here to see the map.
Click here for Level 1 random encounters.
PDF of Level 1: A collected pdf of all the Level 1 encounters is available. Go to the Store to find the download. All members with a yearly subscription can download this pdf for free. Quarterly and monthly members need to pay a small fee. (This is to keep things fair to those who are subscribed for a year, so that someone can't come along, subscribe for a month, easily download all the content for free, and then leave.) This feature is only for those members wanting the convenience of a single file with all the encounters. All members can still access the content of the site as normal.
New here? If you are not yet a member, you can see a preview by looking at area 1, area 2, area 3, area 4, area 5, and area 6.
Art by Eric Lofgren