Standing in the center of the Dock is a large, cylindrical tower housing Zion's traffic control and defense headquarters. The tower is many hundreds of feet tall and has dozens of long bridges that branch out to the edges of the dock, leading to Zion's living quarters, energy production machines, the Temple and the Council Chamber. The tower is also fortified with heavy gun turrets, used extensively during the Battle of Zion.
During the Battle of Zion, the Dock was the primary assault area of the Machines' army of 250,000 Sentinels. Large drilling machines burrowed their way into the Dock through it's high ceiling, crashing to the lower levels, a successful strategy that enabled them to avoid Zion's tunnel defenses. The Sentinels swarmed in seconds later and quickly gained the upper hand in the battle. Finally, the Dock was temporarily saved when the Hammer entered and fired off an EMP, killing the Sentinels, but also frying the defense systems. It was quickly overrun by the second wave, but was liberated when the Machine Army left.