It's the year 222 now, so about 22 years after I started digging the ground. I first lived completely underground, then made a small structure with some fortifications to defend myself.
I have recently decided to expand my territory and fortify a large area with gates and walls all around.
In any case, here is the situation:
The larger structure on the right is my pump/aquaduct building and transfers water to an underground reservoir. The flatter structure it is connected to was my original building after I decided to expand above ground. It currently houses the statue garden, trade depot, military supplies and barracks.
On the left, the long flat structure is still under construction (well, just the roof). This is my ballista range, where I have a bit of fun with ballistas against tight groups of goblins in the event of a siege/ambushes. I've pretty much done away with the traps, though I have put an artifact mechanism to use in there with 10 large serrated disks.
Anyway, I have a lot of unused open space. Currently, I have a part of it marked for large wood, stone and refuse stockpiles, so it isnt entirely unused.
What could I possibly build here? What I am thinking of is a military structure for all their supplies, catapults for siege operation training and of course the barracks, but this hardly fills up the entire compound.
Perhaps a second option is a suicide tower I come across in many forts, but since I've taken care of every mood requirement and dumped a few artifacts in the dining room, the amount of melancholic, mad and utterly depressed dwarves has dropped by 100%.
I could use some suggestions!
Little note: I have no magma, and water is only acquired through rain transferred by the aquaduct.
Farms have been taken care of through greenhouses. Random crap/mood items are stocked in an underground "warehouse", (bed)rooms have been provided for, and tombs are suitably located deep underground.