CLIC stands for the Compact Linear Collider. Despite a main accelerator of 42 km in length, the accelerator is “compact” due to its high accelerating gradient of 100 MV/m. To achieve the same centre-of-mass energy with LHC acceleration (5 MV/m) would require a distance of 840 km! Or alternatively, 700 km of LEP2 acceleration (6 MV/m).