Ost Guruth is situated in the Lone-lands, and is a questing hub for levels 20-30, featuring portions of the game's Epic storyline -- but it's more than that too. Exploring Middle Earth hopes to give players an understanding of the lore and history of their favorite zones, and to that end, we learn that the ruins you see now at Ost Guruth belie a mighty past. They were in fact a castle that ended up being a casualty of war... but we won't spoil the details here. You can enjoy the full article via the related story link.
Oh, and since we're just now catching up on Exploring Middle Earth (and the earlier entries were from prior to Massively's launch), check out others in the series such as Barad Gúlaran and The Eavespires.