Araharum

Legend has it that Araharum was either the name of a floating Juthannan city over what is now known as The Arum Swamp, or the wizard who caused the city to fall, perhaps even caused the ruin of all of Juthanna, but the details have been lost to time. What is fact is that at one point in time a city had been raised up from the earth below, and eventually this magic collapsed, causing the metropolis to come crashing back down. Between the physical impact and various enchantments coming apart caused hundreds of miles of land to be terraformed into a bog wasteland.
There are still Juthannan ruins to be found there, but exploration is difficult due to the dangers of the swamp, the rarity of the ruins, difficulty in gaining access to them, and how well they and any artifacts contained therein were preserved.