Star CairnsThe Lost Tombs Series is a pretty good module series that take place in the world of Greyhawk but a couple of quick modification and you can place this in Mystara very easily, right now I have chosen as a prime location the region of Ylaraum, because of the simple fact the The Cairns History would be easier to explain if I modified it to make it a part of the mysterious history of Nithia. These cairns location in Ylaraum would also make it a perfect chance to introduce the characters to maybe certain members of Barimoor's network, for which he might be using one or all of them, your choice to work on his quest for immortality, and now my recommedation as to where to place the Lost Tombs Series of Greyhawk in the Known World.
The Known World Version
After Studying my maps of the Known World of Mystara, I believe the best choice to play the Star Cairns would be The Emirates of Ylaruam, in the Northern Highlands of the Emirate of Nithia. My choices in Ylaruam falls on two areas in that emirates and the origins of that region is steeped in the history of the ancient Nithian people
ORIGINS OF THE CAIRNS IN THE EMIRATES
The Star Cairns were created by the Court Mage of a Pharoah called Murturahotep, who read the book of the Scarlet Sign. He wished to restart the war between Nithia, and Ancient Alphatia of the past. Murturahotep decided to creat the Star Cairns in the Northern Highlands of the Ancient Nithian Empire, after discovering a Magical Ore Vein in the Northern Highlands. He ordered the creation of these cairns, later casted a spell of forgetfulness using the pearl of oblivion to force all workers to forget the purpose, and the location of these cairns. Murturahotep and his college of mages went to work for 5 years creating magical items for their upcoming war until Murturahotep died attempting to become a lich during his bid for immortality. Bu his work continued until the fall of the Nithian Empire. Mages sensing doom for Nithia, fled west to help the mages who created cinnabryll to forge a new Nithia, unfortunately this failed miserably.
The Syndicate, a secret group of heroes of the Known World representing each nation of the Civilized Nations of the S. Known World, mostly members of the Western Defense League, both past and present, who defend the KW from any successful attempt for Hulean Domination as well as Internal Chaos between nations of the KW. Karameikan Mystic, Stefana Petrovska Discovered omen of doom for the WDL, starting first with the sighting of dark dwarves appearing on the Ylaruam/Soderfjord Border, these Dark Dwarves are known as the Mad Modrigswerg Dwarves although the Duergar can also be used as well. The Mysterious Stone Windmill of the Shires is aproaching it's zenith by another degree. Already the Syndicate has warned the nations of Darokin, the Five Shires, Karameikos, and the Empire of Thyatis as well as other nations bordering Karameikos. The Adventuring Guild of Ierendei was also informed as well, to search in the Northern Highlands of Ylaruam, this can be hard with the isolated attitude of the Abbishai of the Eastern lands of Ylaruam. To look for anything that would prevent a disaster from striking Darokin first, and spread throughtout the rest of the KW bordering Darokin.
THE CAIRN INFO.
The locations of the first cairns can be up to the DM, these cairns are 15-20 apart in a diagnal direction, for location A. you can plan start by placing Cairn D. the Doppelganger Cairn, 12 to 16 miles due East of Cinsa-Men-Noo and place the Fifth Cairn at the foot of the plateau. For Location B, put the Necromancer Cairn, 16 miles Northwest of Surra-Men-Raa. This cairn can give background information of the ancient Bedouin Burial Cairn, during the time of occupation, and place the Astral Cairn at the southern point of the Highlands, 32-36 miles north of Jaboor. The Cairn Inhabitants of the past will attack those of Non-Nithian origin. (Dusky Skin, Black Hair, and Dark eyes.)
The module can run as normal, with the group of doppelgangers, who are running away from Ylari Aggresion from the Kin faction's Jihad to destroy all unnatural being who mimic humans, and infidels who don't worship Al-Kalim. Now a member of the Doppelgangers group, working within a member of the Town's Merchant Guild as a man, since women are considered inferior in Ylari society.
The Cairn was used by Alphatian Nobles during the occupation period, and the Ylari Beduoin as a burial tomb. It is considered a sign of prestige for a Noble of either origin. The Necromancer is a Thyatian Adventurist trying to learn some Nithian secrets and be accepted as an instructor at the Karameikan School of Magecraft in Krakatos. She can persuaded to adventure into the lower levels of the cairns for a price. Unfortunately, in the future, her membership will be rejected by Terari after he discovers that the cairn also held remains of Ancient Alphatian Nobles as well.
Runs this cairn as normal, with a minor modification of having the Derro replaced by the Modrigswerg Dwarves if you wish, although the Derro can be a bigger challenge.
Run this module as normal.
RUNE PIECES CLUE TO THE LOCATION OF THE TOMB OF LYZANDRED THE MAD
Use all runes except for pieces from the Golem Cairn and the from area D15. The pieces translate as followed
The Hammer represent dwarven mines. The O represents Parsa, The oasis Represents Sulba, before it's creation, and the cat's head Represents Deraan, when in Nithian were part of the cult of Bastet.
This should be placed in a hidden valley in the mountains of Rockhome, This region should be very isolated, and can be run as a stand alone Module, it should run as normal and it's clue should lead the characters to the either the Shires or any place where you wish to put a windmill, In my opinion i think that the Shires or The Southern Darokin Region like Near Athenos/Mar or the Fort Blizzard pass region between Hinmeet and Ringrise. This should be a good conversion for you to try. I will come back at a later date to pick region of the Savage frontier to put the these module from the Greyhawk Trilogy. Thank you.