During open beta i also took my time to explore the Inevitable City a bit further. To the east is an arena type structure which contains also the entrance (or better three) to one of the first PvE dungeons. The Inevitable City has three dungeons: The Sacellum, The Bilerot Burrow and The Bloodwrought Enclave. While some of the dungeons only will open up later (how can you check the city rank btw?), this one is open from the start. The Sacellum dungeons got three different entrances:
East entrance - starting with rank 13 (beastman/khorne themed)
West entrance - starting with rank 15 (ogre themed)
Middle entrance at the arena bottom - starting with rank 17 (no solid theme but has a dragon and hydra)
While i only was only able to check out the entrance area of each wing, and beside a few rats did no go past the champions down there, others like Keen were able to venture into it. I also found a video about some boss fights in there. From the little info i could gather it's adviced to bring at least some kind of off-tank with you. The different three wings (designed for group'o'six gameplay) are fairly short and house a few bosses. The last boss of each wing will drop a set piece. So far i only found one quest "Grobbit's Errand" (found in Barak Varr) for the Sacellum, but i heard rumours about another one possible to pick up inside the arena middle somewhere. Once I'm the appropriate level again I'll make it my mission to adventure into the dungeon and post more info on it.