I started working on this map a few weeks ago, and just recently starting adding to it again. It is one of my first maps, so I'm learning as I go along.   
So far I have the following done:   
Armory (attached to the ceiling, has a monitor for watching prisoners in isolation). 
Catwalks (attached to the armory and has ladders down to the floor). 
Medic (heals at a rate of 10 HP per second). 
Cells (Each have a toilet, bed, and light + possible extra "goodies" ). 
Isolation (monitored by a destroyable security camera). 
Pool (the dimensions of an Olympic swimming pool, and has a drivable boat in it). 
Big Cage (nothing exciting going on in there).     
These are "done" in the sense that they are working, but they'll probably change drastically by the final release.   
I plan on adding the following:   
Execution chambers 
Yard 
Disco 
Shot for Shot room 
Grenade duel room 
Soccer   
Oh, and here are some screenshots in a slideshow!