Greywater Fastness was one of the Seeds of Hope built in the Greywater Reach in Ghyran through the Festermere Realmgate. It's a towering stronghold of ironclad walls, roaring furnaces, sorcerous wards and lowering cannon batteries. The city is built upon a vast reserve of Ghyran realmstone that is used to power the growth of the city. 
Currently it is a city that never sleeps, its industry unhalting. To this day Alarielle is still trying to retake the city's grounds via raining fast-growing plants that require fast removal. Its streets are described as narrow rivulets of stone and metal, remnants of a tireless, ever-expanding industry. These streets widen as they approach to the great canals that connect the city with its surrounding marshes. 
This city was only possible after Valius Maliti made the intuitive leap of using realmstone as a power source and his genius combined with the the wisdom of the aelven enchanters, and the pragmatic skill of the Ironweld engineers the harnessing of Ghyranite realmstone began with arcane machinery. Suddenly a collective of artisans and labourers poured through the Festermere Realmgate into Greywater Reach with the protection of the the Anvils of the Heldenhammer, the Eldritch Council and regiments of Freeguilds, especially those of the Greycap gun companies. The bog-grot tribes that had harassed their stockades were driven back by crackling war machines, the swamp waters were drained in days and and the land was baked into hardened clay. Walls and towers increased in size as the region's resources were plundered to built the fast growth of the city. The horrified Sylvaneth even came to blows with their allies as trees were felled by hundreds to fuel the growth of the city.[4a]
During the Season of War, hordes of beastmen threatened to tear the city down and the guildmasters ordered a full salvo from its macro-Hurricanum arrays creating an arcane detonation that not only utterly wiped out the besiegers, but also turned the surrounding verdant landscape into a desolate, smog-choked wasteland. The Dreadwood Sylvaneth led by the Treelord Pale Oak move to occupy the devastated territory now known as the Ghoul Mere and refused to allow people passage out of the city. In the aftermath of another bloody conflict negotiations are held and the city secured a single trade route out of the Fastness which becomes a militarised highway and those who stray from this path are taken away by woodland spirits.[5a]
Like most Cities of Sigmar the Greywater Fastness is ruled by a Grand Conclave. However the Council of the Forge, a great gathering of lords and clan chiefs mainly from the Dispossessed clans and Ironweld Arsenal wields more power than the Grand Conclave. The council is driven by the desire for more resources to power their experimental war machines and seeks any excuse to make war upon Greywater’s neighbours.[5b]
The main force that drives the expansion of Greywater Fastness is war. The high demand for Greywater weapons and refined firepowder keeps wealth flowing to the Ironweld guildmasters and Dispossessed mason-lords and keeps the fires of the gun foundries ever blazingthe. The duardin clans that operate some of the most prosperous forge complexes have even become wealthy and powerful enough to earn a position on the Council of the Forge.[5b]
Greywater Fastness is a highly advanced location, with clockwork automatons used for commoner (if well to do) transportation. These are known as rattletraps, a steel-rimmed carriage pulled by a steam-powered automaton wrought crudely in the shape of a horse.
The standard doctrine for the generals of the city is the decisive application of overwhelming and often extravagantly excessive. firepower. Elite regiments of Freeguild Handgunners known as Greycaps for their distinctive headgear join with veteran shieldbands of Dispossessed Ironbreakers and Irondrakes. Relentlessly drilled, these troops form an nearly impervious battle line. The infantry are backed up by the might of the Ironweld Arsenal with cannon and Helblaster Volley Gun batteries with bomber squadrons flanked by whirring Gyrocopters.[5b]
- Cathedral Hill 
- Old Fen Gate: The first gate built over one of the largest and oldest of the canals and it used to mark the end of the city. The the walls expanded long ago and it became a haven for criminals. 
- Mere Keep: A powerful fortress gateway , constructed by duardin stonemasons of heavy black stone dredged from the marshland., it has a dozen heavy portcullises and batteries of cannon. The walls and gun towers stretch out on either side of the might gate house and loop back towards the road to the city. It has stables, animal pens and a forge and is as self sufficent as possible. [6a]
Several million people of various races live in the city. [6a] The people descended from the orginal natives of the area are known as Jade-Bloods, whereas those descended from the first settlers from Azyr are knwn as star-bloods.[6b] Whilst slavery is illegal, prisoners are often formed into work-gangs, sent eleswhere on to the smalle settlements in the Mire, some are used to form penal regiments or press-ganged into crewing ships. [6b]
- Palem Bok: Bookseller and spy for Queen Neferata in Greywater Fastness. Intervened successfully in the Auction of Blood and acquired Charu, the Soul-Lash.
- Casper Guno: well known and feared Crime boss. [6b]
- Shayl: Aelf and former security guard of the Old Fen Gate's illegal underground, the Magpie's Nest. Currently in Pallen Bok's service.
Flora and Fauna
- Fellwater Troggoths: These haul themselves out of the filthy canals, their flabby, scaled flesh encrusted with barnacles of ossified filth and rampage through the slums, attacking anyone foolish enough not to seek shelter.
Ironweld Cog Sigil of Greywater Fastness
- 1: Season of War gaming aid from the WH AoS app, A New Power.
- 2: Auction of Blood by Josh Reynolds
- 3: Greywater Fastness product listing
- 4: Age of Sigmar: Core Book (2nd Edition)
- 4a: The Seeds of Hope, pg. 54-55
- 5: Battletome: Cities of Sigmar (2019)
- 6: Dark Harvest (novel)
- 7: Soulbound Core Rulebook
- 7a: The Mortal Realms
|Cities of Sigmar|
|Founding Cities||Anvilgard (Har Kuron) • Excelsis • Hallowheart • Hammerhal • Tempest's Eye • Vindicarum|
|Seeds of Hope||Greywater Fastness • Living City • Phoenicium|
|Free Cities||Alshime • Anvilheim • Arbitrium • Blackwall • Brighthall • Brightspear • Catransa • Celestrius • Colostrum • Darkdelve • Draconium • Glymmsforge • Gravewild • Greenfire • Greyspire • Helmgard • Izalend • Kurnothea • Lethis • Matarka • Mhurghst • Misthåvn • Seven Words • Settler's Gain • Skythane • Taberna • Thraesh • Umbramox • Vandium|
|Scion Cities||Phoenicium: Holdash • Houndsgate|
| Cities of Sigmar
|Collegiate Arcane • Darkling Covens • Devoted of Sigmar • Dispossessed • Freeguild• Ironweld Arsenal • Order Serpentis • Phoenix Temple • Scourge Privateers • Shadowblades • Wanderers|
|Associated Factions||Eldritch Council • Daughters of Khaine • Fyreslayers • Kharadron Overlords • Lion Rangers • Order Draconis • Stormcast Eternals • Swifthawk Agents • Sylvaneth|