This is the seventh map in the set, you can find links to the rest at the blog post.
In this portion of the undercity we see many of the elements that make the undercity what it is
This map segment is built up around two key features – the first is the sewer line that starts in 1F and runs through 1E before coming into this map segment. Attached to this sewer line is an access corridor (that also links into a large crypt back in map 1E that may or may not have access to a temple or clanhouse above). A basement access leads into two different secret entrances to the sewer line – probably used by thieves, smugglers, or a cult that doesn’t have easy access to one of the ruined areas.
The other key feature is a partially collapsed structure from the ancient city that became the undercity over the years. The collapse in question is actually fairly recent, as it not only affects this structure, but some of the sewer lines to the north as well – perhaps caused by water damage from the sewers almost running through this old building. Now this level of the structure is almost completely inaccessible, cut off from the rest of this part of the undercity by the extensive collapsing except via a secret access concealed in the floor of one of the sewer access lines (the secret door in question is actually a collection of stone bricks placed over a reinforced wooden slat that can be pushed up from below requiring a lot of force, or opened from above by first removing the bricks).
This particular structure was once an administrative building of some sort, with a number of cells around the level that were used to store, read, and scribe documents important to the operations of the clan who once operated here. Some of these documents may be useful to trace ownership of lands or locations of lost treasures, others might include spells either lost to the ages or specific to the temple of the god of the old clan.
Of more interest to most underworld explorers is the massive hole in the floor of this partially collapsed level, one of only a few means of access between this level of the undercity and deeper levels below.
You can download this part of the My Private Jakalla megadungeon project (and find links to the previous six maps) from the blog post at http://wp.me/psUVp-2rz