Cathedral earned its name from the towering spires that crown its upper hull, rising nearly twenty stories above the prairie. The machine walks on four massive pillar-legs, each one a complex assembly of hydraulic pistons and armored housings that slam into the earth with enough force to register on seismographs three hundred kilometers away. Between the spires, arrays of antenna-like structures broadcast continuous signals on frequencies that no known receiver can decode. The transmissions have been ongoing since before anyone alive can remember.

The machine's central body is a cathedral-sized hall of exposed machinery, visible through gaps in corroded armor plating where repair systems haven't quite kept up with decades of weathering. Through these gaps, observers with telescopic equipment have reported seeing rows of manufacturing arms assembling components on internal conveyor systems — building things, endlessly, that never seem to leave the machine. Some speculate Cathedral is constructing something inside itself, adding to its own complexity with each passing year. Structural analysis suggests the machine is measurably larger now than it was in photographs from 2165.

Cathedral's broadcast signal is its most unsettling feature. Every automaton within reception range — commercial, military, industrial — experiences behavioral anomalies when Cathedral passes. Security drones deviate from patrol routes. Factory robots pause mid-task. Service automata turn to face the signal source. The effect is temporary and poorly understood, but it has led to Cathedral being classified as a priority avoidance target by every corponation operating in the region.