Following up on the forum thread with the same name, I created a simple mod, placing monuments of all the lost settlements that disappeared some time before the events in Skyrim:
Amber Guard, Amol, Bardmont, Blackmoor, Dragon Wood, Dunbarrow, Dunpar Wall, Dunstad Grove, Granitehall, Greenwall, Helarchen Creek, Karthwasten Hall, Korvanjund, Lainalten, Laintar Dale, Markarth Side, Neugrad Watch, Nimalten City, North Keep, Oakwood, Pargran Village, Reich Corigate, Snowhawk, Stonehills, Sunguard, Vernim Wood, Volunruud and Vundeheim.
This is just my interpretation of the Arena map of Skyrim, known distances in the game Arena, and settlements mentioned in literature.
Each monument consists of a pillar, blue fire on top, and an etched tablet, which reads "In memory of the lost settlement/city-state of ...".
Skyrim Special Edition
(tested with SSE 1.6.640, but may probably work with all 1.5.x and 1.6.x versions)
No known conflicts, but there may be conflicts when other mods use the location of any of the 28 memorial pillars. At least in my mod build, there are no conflicts with Scandinavian Forests, Dense Nordic Forests, Inns and Taverns, Ranger Cabins.
You are not allowed to upload this mod to other sites under any circumstance or without my explicit permission. All assets in this mod belong to the author.
The ESP can be turned into ESL by compacting FormID's first and then adding the ESL flag to the TES4 header.
Creation Kit 2.0
7-Zip File Manager