Towards the end of the war, improvisation was the rule rather than the exception. Their sleek wings of the ballistic interceptors had long since taken their last flight, and this left a surplus of tractor chassis. Some of these were used in the final defense of the capital, including this example. It's been fitted with an outmoded field gun and its associated fortress mount, giving a marginal degree of mobility to weapons salvaged from the bypassed coastal emplacements.
Sighting would (ideally) be done by an associated survey team, or forward observer in the case of tactical targets. In the end, the Goliath serves as more of a monument to Protectorate desperation than as an example of a useful battlefield asset. Most of the thirty or so examples completed were either destroyed by counterbattery fire, or abandoned after mechanical failure or running out of fuel.
The depicted example was abandoned and overrun in a cornfield just south of the capitol, near the Palace of the Engines. The peculiar mechanism above the barrel is for muzzle loading two-piece rocket projectiles instead of normal shells.