Jomsborg, we learn as we enter the quasi-educational exhibition at LEA27 created by Lor Asynja (Lor Pevensey), Lisa Asynja (Lina Fonda), Maxje Constantine (Maxje Ryada) and perhaps others, was a Viking ring fortress. "Viking ring fortresses were circular forts built by the Vikings in the Viking Age," we're cheerfully informed, and that sentence captures the high-school level (perhaps I'm being generous) writing, replete with typographical and grammatical errors, that populates a museum-like area overhead the replica build on the ground. Or at least we might hope it's something based on research — after all, the creators do admit, "This is our vision of these Viking ring fortresses which might or might not be accurate." (We also learn that the Venus de Milo had Viking-related graffiti on her saying "Lisa was here." Huh?) One hopes also that the creators had permission to use all the various images in their displays.
As you learn about Viking history — such facts as, "Erik killed some people in the 950's in Norway and did what many other killers did. He moved to Iceland. But he got in trouble there and also had to move." being indispensable — you can teleport down to a build on the ground, much of which, despite being mesh, resembles simple builds constructed of prims from around 2007. Perhaps I'm being a little too harsh here, as one does get to see (maybe) what a Viking ring fortress looked like, and no doubt the creators made every effort to do their best. But my suggestion: you'll do better looking elsewhere.