Cooper's Exit

Cooper's Exit is a supposed secret exit located at the very bottom of Halcyon that eventually leads to the outside world, theorized to have been discovered and used by Hayden Cooper and his rebels twenty-five years following the Great Collapse. The Exit has never been confirmed to exist, and it is generally believed to be a myth among the city's populace.

Overview
The appearance of the Exit is completely unknown, with only a little information surrounding it. It supposedly leads into a marked route through the tunnels below Halcyon's farthest reaches, at depths of 20-25 miles or more, before ending in an elevator platform leading up to the surface. It is entirely possible and likely that the Exit does not even exist, and was merely a story made up by Cooper and his followers to strengthen the morale of his people as they fought their way to the bottom of the city.