Anyone know when Archlis was established/founded?
Many thanks.

I'm not aware of there being a founding date for Archlis in any published Blackmoor material. But it's at least old enough for Skelfer Ard to have grown up there (DAB, p. 69). Since he discovered/invented the spell focus in 886 (DAB, p. 96), the town must have existed well before then. It was destroyed in 894 (DAB, p. 96), but it was obviously rebuilt at some point after that.

OT

On this site you can find a beautiful amateur map of Archlis, showing the old city that was destroyed and the new buildings: viewtopic.php?f=22&t=7762

If you are interested about the MMRPG, Episode 55 Crab Coast Clash is set around Archlis.
In my campaign, I adapted the adventure The Floating Dungeon of Varrak Aslur (from another / a generic campaign world) to Archils and it worked out pretty well: viewtopic.php?p=36041#p36041