Nanotech Swarm

Some technologies have been abandoned or neglected. One of the few that's been focused on and advanced is that of nanotechology. By the time The Folly occurred, there had already been several breakthroughs. With the focus given to it during and since The Exfil Edict, the field has advanced by leaps and bounds. Swarms of nanites are now ubiquitous throughout the Great Retreat.

Architectural Applications

Nanotech swarms show up in multiple ways in both the exteriors and interiors of any Megastructure. During the initial construction of them, nanotech swarms worked in conjunction with large scale machinery to cannibalize existing cities and municipalities to aid in gathering materials and the construction itself.
Once the megastructures were in place, nanotech swarms were deployed as "skins" for the massive buildings. These skins serve many purposes, including but not limited to...

• Sensor arrays for data collection.
• Energy collection, especially solar.
• Integrity preservation and repair.

Within the buildings, they serve similar purposes, along with...

• Data storage and communications networks.
• Reactive material for artistic work, both public and private.

Personal Applications

Individual residents of the megastructures are also inoculated with their own personal nanotech swarms. These swarms work inward to preserve the health of their hosts (including functioning as a backup and augmented immune systems). They also work inward to allow the Exfil to interface with the megastructures themselves.
NOTE: This is how punishments such as being Shadowed are possible.

Progress & Consequences

The nanotech swarms have been expanded and improved over the course of the Great Retreat. This has largely been positive and is the reason there have not been any pandemics within the megastructures. But it is also what led to both the creation of The Dead Floor and the continued survival of The Carrion, though this is not known to the population at large.