If explorers of Skyrim's south-eastern frontier speak truth, Skyrim's timed Xbox exclusive DLC packs may take us back to the realms of Morrowind and Cyrodiil, settings for Elder Scrolls 3 and 4 respectively.
Foraging around Stendarr's Beacon, which lies on the border with Morrowind, one such adventurer discovered a path leading to a stone archway and an invisible wall. Using fiendish technical arts, he was able to penetrate beyond and discover scaled-down, low resolution models of Morrowind's Solstheim and Vvardenfell and Cyrodiil's Imperial City.
Check out this Tumblr account for the full story - we've ported over a few of the snaps. The intrepid user posits that the landmasses could have been modelled simply to give PC modders geography to play with, or to fill out the 3D map screen.
Bethesda has kept schtum on the subject of Skyrim DLC, with game director Todd Howard commenting only that there will be less of it, but that individual packs will be more "substantial". Marketing and PR boss Peter Hines has said that Bethesda doesn't believe in carving out content for DLC ahead of release.
Assuming those hidden locations are, in fact, on-disc DLC, it seems probable the first Elder Scrolls 5 expansions will give players the chance to explore how Skyrim's neighbours have aged in the time since previous games.