The ACT is an off-axis Gregorian telescope, with a primary mirror and a secondary mirror. Both mirrors are segmented, consisting of 71 (primary) and 11 (secondary) aluminum panels. Unlike most telescopes which track the rotating sky during observation, the ACT observes a strip of sky, typically five degrees wide, by scanning back and forth in azimuth at the relatively rapid rate of two degrees per second. The rotating portion of the telescope weighs approximately , creating a substantial engineering challenge. A ground screen surrounding the telescope minimises contamination from microwave radiation emitted by the ground. The design, manufacture and construction of the telescope were done by Dynamic Structures in Vancouver, British Columbia.