Cyclonus is a city built upon the whirling cyclonic cloud system of an eternal hurricane generated by the SPP tower network. A large, sprawling metropolis, the city itself is built around the eye of the storm and comprised entirely of buildings constructed with pegasi cloud architecture. Cyclonus is constantly moving, and travels in a long, slow circuit north over Equestria's west coast before turning to head west out over open ocean, finally traveling east in the final leg of its journey and returning to land to complete its orbit.
As Ardent Vortex's home city, it was also the city that held most of his supporters. Several years prior to Mach's descent beneath the clouds, Ardent Vortex was working to overthrow the Enclave leadership by rallying pegasi of like-minded viewpoints to his cause. Not wanting to lose control of their citizens, the Enclave High Council authorized a black operation to assassinate Vortex.
Although the assassination was thought to have succeeded, it did not go off without complication. In order to pursue the fleeing Vortex, Mach was forced to leave his military-issue hardware behind, where it was to be discovered by the citizens of Cyclonus, further stirring up the already-rebelling pegasi. The Vortex Rebellions would continue for some time after his alleged death, before they were finally quelled by the Enclave government's military.