To give you a quick breakdown if I remember correctly, the four round circles were pillars that went all the way up to the ceiling so they would completely block line of sight from certain angles. The two cylinders in the middle that have stairs leading up from the sunken in pit were essentially bunkers that kept spawning battle droids if the players didn't capture and hold them. The turret was a hazard that fired at the top of every round which could only be disabled from the control panel on the inside of the citadel. You could climb up the front wall right up to the top, or climb up the stairs and slice through the blast doors. My players had a lot of fun with this encounter and to this day say it is one of the more memorable encounters they have ever experienced.