Ladders were not able to be deployed from the walls of the city, or from the ground to any of the rooftops. Basically the top of the roof was invisible and the ladder would "fall into" the roof about 3 feet making it impossible to get up top.
When DRZ was spawning on the roofs and your ladders on the defense side go through buildings, it's kind of hard to defend. DRZ literally had catwalks above the defenders walls and city because every defender ladder clipped through walls and roofs.
Fixing that would be pretty cool.